04350040 is referenced by 17 patents and cites 9 patents.

A multiple segment three-terminal type capacitance probe with segment selection, capacitance detection and compensation circuitry and read-out control for level/density measurements in a fluidized-bed vessel is provided. The probe is driven at a high excitation frequency of up to 50 kHz to sense quadrature (capacitive) current related to probe/vessel capacitance while being relatively insensitive to the resistance current component. Compensation circuitry is provided for generating a negative current of equal magnitude to cancel out only the resistive component current. Clock-operated control circuitry separately selects the probe segments in a predetermined order for detecting and storing this capacitance measurement. The selected segment acts as a guarded electrode and is connected to the read-out circuitry while all unselected segments are connected to the probe body, which together form the probe guard electrode. The selected probe segment capacitance component signal is directed to a corresponding segment channel sample and hold circuit dedicated to that segment to store the signal derived from that segment. This provides parallel outputs for display, computer input, etc., for the detected capacitance values. The rate of segment sampling may be varied to either monitor the dynamic density profile of the bed (high sampling rate) or monitor average bed characteristics (slower sampling rate).

Title
Capacitance-level/density monitor for fluidized-bed combustor
Application Number
6/163368
Publication Number
4350040
Application Date
June 26, 1980
Publication Date
September 21, 1982
Inventor
Carroll E Utt
Morgantown
WV, US
George E Fasching
Morgantown
WV, US
Agent
Richard G Besha
Stephen D Hamel
David E Breeden
Assignee
The United States of America represented by the United States Department of Energy
DC, US
IPC
G01R 27/26
G01F 23/26
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