Optical device for monitoring clarity of a fluid
First Claim
1. An optical device for monitoring the optical clarity of a fluid comprising a source of light which projects a beam across said fluid, a measurement photosensitive element having a light-accepting window disposed in the path of the projected light beam after it has passed through a substantial portion of said fluid for providing a measurement signal which represents the amount of said projected light beam passing through said fluid, a reference photosensitive element having a light-accepting window disposed closely adjacent said source of light and in the path of light projected through said fluid for providing a reference signal, a reference integrating electrical circuit connected to said reference photosensitive element for collecting and storing said reference signal, a measurement integrating electrical circuit connected to said measurement photosensitive element for collecting and storing said measurement signal, switching means having a predetermined tripping signal parameter, said switching means having an input connected to said reference integrating circuit, said switching means having an output connected to said measurement integrating circuit for disconnecting said measurement integrating circuit from said measurement photosensitive element to terminate collection and storage of said measurement signal, and readout means connected to said measurement integrating circuit for providing a reading of the measurement signal stored in said measurement integrating circuit during the period required to trip said switching means whereby the clarity of said fluid is indicated.
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Accused Products
Abstract
The measurement and reference photocells of an optical detector for a smokestack are disposed adjacent each other on one side of the stack. The measurement photocell and its light-accepting window are disposed on the opposite side of the stack from the light source and the reference photocell has its light-accepting window disposed closely adjacent the light source. A light conducting conduit extends through or around the smokestack within a casing which shields and conducts the light directly emitted from the light source to the reference photocell. Purging air flows within the casing and outwardly through the windows to prevent soot from collecting on them, and the windows are shielded by perforated covers which equalize the flow of air over their entire area and maximize velocities for a given air flow. Wire mesh screens of rounded wire generate a Coanda effect around their outer contours which helps prevent soot from settling within the openings. The reference photocell is connected in a reference integrating circuit having a predetermined switching parameter. The measurement photocell is also connected in a measurement integrating circuit having readout means. The switching means for the reference integrating circuit is connected to the measurement integrating circuit to trip it off after a predetermined amount of light has been detected by the reference integrating circuit. The readout is a measure of the amount of light received by the measurement photocell while the predetermined amount of light is received by the reference photocell and accordingly represents the clarity of the fluid. The integrating circuits may be capacitive networks with voltage comparator and operational amplifiers, and the switching means for operating relays to obtain a readout from the measurement integrating circuit and to reset both of the integrating circuits is effectively provided by a silicon controlled rectifier.
41 Citations
30 Claims
- 1. An optical device for monitoring the optical clarity of a fluid comprising a source of light which projects a beam across said fluid, a measurement photosensitive element having a light-accepting window disposed in the path of the projected light beam after it has passed through a substantial portion of said fluid for providing a measurement signal which represents the amount of said projected light beam passing through said fluid, a reference photosensitive element having a light-accepting window disposed closely adjacent said source of light and in the path of light projected through said fluid for providing a reference signal, a reference integrating electrical circuit connected to said reference photosensitive element for collecting and storing said reference signal, a measurement integrating electrical circuit connected to said measurement photosensitive element for collecting and storing said measurement signal, switching means having a predetermined tripping signal parameter, said switching means having an input connected to said reference integrating circuit, said switching means having an output connected to said measurement integrating circuit for disconnecting said measurement integrating circuit from said measurement photosensitive element to terminate collection and storage of said measurement signal, and readout means connected to said measurement integrating circuit for providing a reading of the measurement signal stored in said measurement integrating circuit during the period required to trip said switching means whereby the clarity of said fluid is indicated.
- 17. Apparatus for measuring the clarity of a fluid sample comprising means for transmitting radiant energy into said sample, first means for detecting radiant energy from said transmitting means after it has passed through a substantial portion of said sample, second means for detecting radiant energy from said transmitting means after it has passed through a much smaller portion of said sample, means responsive to the energy detected by said second detecting mans for establishing a measurement period, and indicating means responsive to the energy detected by said first detecting means during said measurement period.
- 27. Apparatus for determining the clarity of a fluid sample comprising means for transmitting radiant energy into said sample, first means for detecting radiant energy from said transmitting means after it has passed through a substantial portion of said sample, second means for detecting radiant energy from said transmitting means and for establishing a corresponding measurement period, said first detecting means having means for producing a signal which is substantially an analog of the energy detected thereby, and means for accumulating said signal substantially continuously during said measurement period.
Specification