Multiple gas property sensor
AssigneeNiagara Mohawk Power Corporation
InventorsUlrich Bonne, Robert J. Matthys, David Kubisiak
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Abstract
Transducer apparatus and related method are described for substantially simultaneously determining pressure and one other property (or property combination) of a flowing gas of varying pressure and composition. The technique utilizes several empirical algorithms for correlating the frequency and series resistance of a crystal resonator exposed to the test gas with the desired properties. The apparatus and method can be readily incorporated into an on-line heating value determination process such as that set forth in the referenced co-filed application.
Claims16
Transducer apparatus capable of determining pressure and at least one other property of a test gas, said apparatus comprising:
- a reference vibrator sealed within a chamber having a fixed gas pressure and density;
- a detector vibrator exposed to the test gas surrounding the transducer;
- first means for comparing the frequencies of said reference and detector vibrators and for producing a signal proportional to the difference in the frequencies of said vibrators;
- second means for comparing the series resistances of said reference and detector vibrators and for producing a signal proportional to the difference in the series resistances of said vibrators;
- and
- means for deriving signals representative of gas pressure and one other property of said test gas based upon said proportional differential frequency signal and said proportional differential series resistance signal produced from said reference and detector vibrators.
A method for determining two properties of a test gas having varying pressure and composition, said method comprising the steps of:
- (a) providing a reference vibrator sealed within a chamber having a fixed gas pressure and density, and exposing said chamber to the test gas;
- (b) providing a detector vibrator exposed to the test gas;
- (c) causing each of the reference vibrator and the detector vibrator to vibrate at a resonant frequency, said resonant frequency of the detector vibrator varying with variations in test gas pressure and composition;
- (d) providing frequency signals corresponding to the frequencies of oscillation of the reference vibrator and the detector vibrator;
- (e) comparing said corresponding frequency signals and producing an electrical signal proportional to the difference in said frequencies;
- (f) determining the series resistance of the reference vibrator and the series resistance of the detector vibrator;
- (g) comparing the series resistances of said reference and detector vibrators and producing an electrical signal proportional to the difference in said series resistances;
- and
- (h) deriving signals representative of two gas properties based upon said proportional differential frequency electrical signal and said proportional differential series resistance electrical signal produced using said reference and detector vibrators.
Dependencies are inferred from the claim text.