Optics: measuring and testing – Velocity or velocity/height measuring – With light detector
Patent
1986-03-17
1988-03-29
Buczinski, Stephen C.
Optics: measuring and testing
Velocity or velocity/height measuring
With light detector
7386106, 250239, 250573, 350584, G01P 336, G01P 522, H01J 502
Patent
active
047339624
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a jet velocity measuring apparatus for measuring the velocity of a fluid stream. More particularly, this invention relates to a jet velocity measuring apparatus having a debris-deflecting slot for directing a curtain of air past the respective terminations of light-transmitting fiberoptic bundles of the measuring apparatus.
2. Information Disclosure Statement
U.S. Ser. No. 573,387 by Daniel Parker filed Jan. 24, 1984 and assigned to the Beloit Corporation teaches a method and apparatus for measuring the jet velocity adjacent a headbox of a papermaking machine. All the disclosure of the aforementioned pending patent application is incorporated by reference into the present application.
Copending U.S. Ser. No. 573,387 describes a first and a second fiberoptic bundle for measuring the flow velocity of pulp issuing from a headbox. More specifically, a first light beam passes through the first fiberoptic bundle towards the jet and is reflected back along the first fiberoptic bundle which is bifurcated thereby permitting the reflected beam to be transmitted to a first photosensitive device. The first photosensitive device generates a first electronic series of signals which correspond with that portion of the surface of the stream on which the first beam is reflected. A second beam of light passes through the second fiberoptic bundle towards the jet so that the second beam of light is reflected from the same portion of the stream downstream. The second beam of light is reflected back along the second fiberoptic bundle which is bifurcated enabling the second beam of light to be transmitted to a second photosensitive device to generate a second series of electronic signals. Various electronic apparatus is utilized to compare the first and second series of signals and to measure the time difference between a particular pattern of signals received from the second photosensitive device that correspond with signals received from the first photosensitive device indicating that that portion of the jet has flowed downstream towards the second beam of light. From the measurement of the time taken by such portion of the jet to flow between the first and second beam and knowing the distance between the beams of light, an accurate measure of the jet velocity is determinable.
Prior to the aforementioned copending application, various flow measuring devices had been proposed but most of the prior proposals involved the immersion of a pressure-sensitive device within the jet stream. Such pressure-sensitive devices, of necessity interfered with the smooth flow of the jet of stock of pulp extruded from the slice of the headbox onto the forming wire.
In the papermaking art, a need has existed for a reliable and accurate apparatus for measuring the jet velocity of pulp extruded from a headbox so that such velocity could be adequately controlled in order to approximate the velocity of the forming wire. By accurately controlling the jet velocity to approximately that of the forming wire, the fibers within the pulp are more evenly distributed over the surface of the forming wire.
In addition to the aforementioned pending patent application, another non-contacting flow velocity device has been developed utilizing the Doppler effect in an ultrasonic flow meter. However, an article published October 1985 in Paper Trade Journal, page 42, and entitled "Advancements in Doppler Flow Metering Improve Accuracy And Reliability" by William T. Smith, states that "The Doppler Flow Meter does have limitations. Heavily scaled or coated pipes, excessive pump noise and vibration, pulsating flows, and some hydrocarbon based applications can pose difficulties for the flow meter. Engineers who require extremely accurate readings in high temperature and/or sonically clean applications will currently not select a Doppler Flow Meter." In view of the extremely noisy environment typical of the forming section of a papermaking machine, it is evident that such Doppler Flow Meters h
REFERENCES:
patent: 3903877 (1975-09-01), Terada
patent: 3953126 (1986-04-01), Kim et al.
patent: 4201467 (1980-05-01), Hartmann et al.
patent: 4281646 (1981-08-01), Kinoshita
patent: 4497550 (1985-02-01), Ouchi et al.
Ishida et al., "Measurement of the Velocity and Direction of Flow of Solid Particles in a Fluidized Bed", Powder Technology, vol. 27, #1, Sep.-Oct. 1980, pp. 1-6.
Archer David J.
Beloit Corporation
Buczinski Stephen C.
Campbell Raymond W.
Veneman Dirk J.
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