초록 ▼

A method and apparatus are disclosed for determining the concentration of individual components within a fluid mixture by determining the permittivity of the individual components. The method and apparatus use a reference sensor and at least one measurement sensor positioned inside the same sensor d

A method and apparatus are disclosed for determining the concentration of individual components within a fluid mixture by determining the permittivity of the individual components. The method and apparatus use a reference sensor and at least one measurement sensor positioned inside the same sensor device that is immersed in the fluid mixture to be measured. Signals, such as radio frequency or microwave, are sequentially transmitted at multiple, known, constant frequencies to and reflected from both the reference and measurement sensor(s). Permittivities of the individual components are determined from these transmitted and reflected signals and information about the concentration of the individual fluids and other compounds within the fluid mixture and the density of the fluid mixture are produced. Repetitive sampling and processing of these signals allow determination and real-time monitoring of the concentration of individual components within a mixture of fluids. The present invention provides self-calibration, accurate frequency maintenance and self-selection of an operating frequency range.

대표청구항 ▼

What is claimed is: 1. A sensor device for determining the concentration of fluid components within a fluid mixture comprising: a) a microcontroller; b) a sensor probe including: (i) a probe body having at least two fluid openings for allowing a fluid mixture to flow through the probe body, (ii) a

What is claimed is: 1. A sensor device for determining the concentration of fluid components within a fluid mixture comprising: a) a microcontroller; b) a sensor probe including: (i) a probe body having at least two fluid openings for allowing a fluid mixture to flow through the probe body, (ii) a measurement sensor within the probe body, the measurement sensor having a measurement electrode in communication with the fluid mixture and a measurement transmission line, and (iii) a reference sensor within the probe body, the reference sensor having a reference electrode in communication with a reference transmission line, wherein a portion of the reference electrode is covered by a reference isolator; and c) an electronics instrument package in communication with the microcontroller, the electronics instrument package having a signal generating/receiving unit in communication with the measurement transmission line and the reference transmission line, wherein the signal/receiving unit reciprocably activates the measurement electrode and the reference electrode to measure a parameter of the fluid mixture at a predetermined frequency, wherein the microcontroller calculates a permittivity of a component of the fluid mixture based on multiple measurements of the measured parameter by the reference sensor and the measurement sensor; whereby the microcontroller determines the concentration of the component in the fluid mixture using the calculated permittivity. 2. The sensor device of claim 1 further comprising a reference temperature detector within the probe body and in communication with the electronics instrument package. 3. The sensor device of claim 1, wherein a portion of the measurement electrode is exposed to the fluid mixture. 4. The sensor device of claim 1 having more than one measurement sensor within the probe body. 5. The sensor device of claim 4, wherein a portion of at least one of the measurement sensors is covered with a measurement isolating shroud. 6. The sensor device of claim 4, wherein a portion of one measurement electrode is exposed to the fluid mixture and a portion of one measurement electrode is covered with a measurement isolating shroud. 7. The sensor device of claim 4, wherein more than one measurement sensor is at least partially covered with a measurement isolating shroud and wherein the isolating shroud of each measurement sensor has a wall thickness that differs from the isolating shroud of any other measurement sensor in the sensor device. 8. The sensor device of claim 4, wherein the electronics instrument package includes a means for automatically selecting the measurement sensor to be activated, the selection based on the measured parameter of the fluid mixture. 9. The sensor device of claim 1 having more than one reference sensor within the probe body. 10. The sensor device of claim 1 having more than one reference sensor and more than one measurement sensor within the probe body. 11. The sensor device of claim 1, wherein a load on the measurement transmission line and the reference transmission line is independently adjustable. 12. The sensor device of claim 1, wherein a length of the measurement transmission line and the reference transmission line is independently adjustable. 13. The sensor device of claim 1, wherein a length of the measurement transmission line and the reference transmission line is substantially equal. 14. The sensor device of claim 1, wherein the predetermined frequency includes multiple frequencies. 15. The sensor device of claim 14, wherein a length of the measurement transmission line and the reference transmission line is substantially equal to a half wavelength of the lowest measuring frequency. 16. The sensor device of claim 1, wherein the measurement electrode and the reference electrode measure at least two parameters of the fluid mixture. 17. The sensor device of claim 16, wherein one measured parameter is an impedance measurement of the fluid mixture. 18. The sensor device of claim 1, wherein a portion of the electronics instrument package is positioned within a thermoelectric cooler, to maintain the portion of the electronics instrument package within a predetermined temperature range. 19. The sensor device of claim 1, wherein the electronics instrument package includes a means for detecting an anomaly in the measurement of the measured parameter and compensating the measurement for the detected anomaly. 20. The sensor device of claim 1, wherein the electronics instrument package includes a means for self-calibrating the sensor device to compensate for an anomaly detected in the measured parameter. 21. The sensor device of claim 1, wherein the electronics instrument package includes a voltage controlled oscillator, a reference oscillator, and a phase locked loop, wherein the phase locked loop matches the phase of the oscillation of the voltage controlled oscillator with the oscillation of the reference oscillator. 22. The sensor device of claim 21, wherein the reference oscillator is a crystal oscillator. 23. The sensor device of claim 1, wherein the electronics instrument package includes: a voltage controlled oscillator that is subject to loading; a means for frequently connecting a known load to the voltage controlled oscillator and detecting a variance in a response of the voltage controlled oscillator between connections to the known load; and a means for correcting the variance in the response of the voltage controlled oscillator. 24. The sensor device of claim 1, wherein the electronics instrument package includes: a voltage controlled oscillator having an original transfer function; a means for comparing a measured transfer function of the voltage controlled oscillator with the original transfer function to detect a variance in the original transfer function of the voltage controlled oscillator; and a means for correcting the variance in the original transfer function. 25. A sensor device for determining the concentration of fluid components comprising: a) a microcontroller; b) a probe including: (i) a body having slots for receiving a fluid mixture, (ii) a reference sensor within the body having a transmission line to the electronics instrument package, wherein the reference sensor has a reference electrode that is activated by the signal generating/receiving unit; and (iii) at least one measurement sensor within the body having a transmission line to the electronics instrument package, wherein the measurement sensor has a measurement electrode that is activated by the signal generating/receiving unit; and c) an electronics instrument package in communication with the microcontroller, the electronics instrument package having a signal generating/receiving unit in communication with the measurement transmission line and the reference transmission line, wherein the signal/receiving unit reciprocably activates the measurement electrode and the reference electrode to measure a parameter of the fluid mixture at a predetermined frequency, wherein the microcontroller calculates a permittivity of a component of the fluid mixture based on multiple measurements of the measured parameter by the reference sensor and the measurement sensor; whereby the microcontroller determines the concentration of the component in the fluid mixture using the calculated permittivity. 26. The sensor device of claim 25, wherein the fluid mixture creates a dielectric layer between the body of the sensor device and the measurement sensor. 27. The sensor device of claim 25, wherein the electrode in the reference sensor is isolated from the fluid mixture and wherein the electrode in the measurement sensor is exposed to the fluid mixture. 28. The sensor device of claim 25, wherein the sensor device further comprises a reference temperature detector imbedded in the sensor device and sealingly connected to the electronics package for monitoring a temperature and a pressure of the fluid mixture. 29. The sensor device of claim 25, wherein the generated signal has multiple frequencies to increase the accuracy of measurements for the individual components within the fluid mixture. 30. The sensor device of claim 25, further comprising two or more measurement sensors positioned in the sensor device to measure different properties of the fluid mixture. 31. The sensor device of claim 25, further comprising two or more measurement sensors differing by using various types of electrical load at the end. 32. The sensor device of claim 25, wherein the transmission lines to the reference sensor and the measurement sensor have a length equal to a multiple of a half wavelength of the lowest measuring frequency. 33. The sensor device of claim 25, wherein the transmission line to each reference sensor and each measurement sensor has an independently adjustable length. 34. The sensor device of claim 25, wherein the transmission lines to the reference sensor and the measurement sensor are substantially the same length. 35. A method for determining the concentration of fluid mixture components comprising the steps of: a) immersing a sensor device into a fluid mixture, wherein the sensor device comprises a microcontroller, a reference sensor and a measurement sensor mounted in a sensor housing, wherein the reference sensor and the measurement sensor include an electrode and a transmission line from a signal source, and an electronics instrument package in communication with the microcontroller, the electronics instrument package having a signal generating/receiving unit in communication with the measurement transmission line and the reference transmission line, wherein the signal/receiving unit reciprocably activates the measurement electrode and the reference electrode to measure a parameter of the fluid mixture at a predetermined frequency; b) providing a substantially identical exposure of the reference and the measurement sensors to a pressure and a temperature of the fluid mixture; c) making multiple, approximately concurrent measurements of a number of identified parameters by the measurement sensor electrode at various predetermined frequencies; d) activating the reference sensor to detect anomalies in the measured parameters; e) applying a compensation factor to the measured parameters to compensate for the detected anomalies; f) calculating a permittivity of each component of the fluid mixture based on the compensated parameters; and g) using the calculated permittivities at the selected measurement frequencies to determine the concentration of each component in the fluid mixture. 36. The method of claim 35, wherein the immersing step further comprises the step of shielding the electrode of the reference sensor from the fluid mixture while exposing the electrode of the measurement sensor to the fluid mixture. 37. The method of claim 36, wherein the making measurements step further comprises the steps of: a) identifying parameters to be measured; b) energizing the measurement sensor electrode; c) transmitting a signal at a known, constant frequency through a predetermined transmission line to the measurement sensor electrode; d) measuring the signal sent to the measurement sensor electrode; e) acquiring and measuring the reflected signal from the measurement sensor electrode; f) repeating the energizing, transmitting, measuring and acquiring steps until at least two measurements for each identified parameter are made for the measurement sensor electrode at the known, constant frequency; g) changing the transmission frequency at a predetermined rate; and h) repeating the energizing, transmitting, measuring, acquiring, repeating and changing steps to produce a predetermined plurality of measurements at predetermined frequencies. 38. A method for determining the concentration of fluid mixture components comprising the steps of: a) immersing a sensor device into a fluid mixture, wherein the sensor device comprises a microcontroller, a reference sensor and a measurement sensor, wherein the reference sensor and the measurement sensor include an electrode and a transmission line from a signal source, and an electronics instrument package in communication with the microcontroller, the electronics instrument package having a signal generating/receiving unit in communication with the measurement transmission line and the reference transmission line, wherein the signal/receiving unit reciprocably activates the measurement electrode and the reference electrode to measure a parameter of the fluid mixture at a predetermined frequency, wherein the electrode of the reference sensor is shielded from the fluid mixture whenever the electrode of the measurement sensor is exposed to the fluid mixture; b) providing a substantially identical exposure of the reference and the measurement sensors to a pressure and a temperature of the fluid mixture; c) identifying parameters to be measured; d) energizing the measurement sensor electrode; e) transmitting a signal at a known, constant frequency through a predetermined transmission line to the measurement sensor electrode; f) measuring the signal sent to the measurement sensor electrode; g) acquiring and measuring the reflected signal from the measurement sensor electrode; h) repeating the energizing, transmitting, measuring and acquiring steps until at least two measurements for each identified parameter are made for the measurement sensor electrode at the known, constant frequency; i) changing the transmission frequency at a predetermined rate; j) repeating the energizing, transmitting, measuring, acquiring repeating and changing steps to produce multiple, approximately concurrent measurements of the identified parameters by the measurement sensor electrode at various predetermined frequencies; k) activating the reference sensor to detect anomalies in the measured parameters; l) applying a compensation factor to the measured parameters to compensate for the detected anomalies; m) calculating a permittivity of each component of the fluid mixture .based on the compensated parameters; and n) using the calculated permittivities at the selected measurement frequencies to determine the concentration of each component in the fluid mixture. 39. The method of claim 38, wherein the activating step further comprises the steps of: a) using, at predetermined times during the process, the reference sensor to determine required compensation factors for the identified parameters; and b) adjusting the identified parameters with the compensation factors. 40. The method of claim 38, further comprising the step of agitating the fluid mixture during the measurement step to provide a more representative mixture of the components of the fluid mixture. 41. The method of claim 38, wherein at least one phase-lock-loop-controlled oscillator circuit is coupled to the sensor device via a transmission line for automatically selecting the operating frequency to be transmitted, modifying the frequency as required to lock the frequency at the desired value and allowing rapid frequency changes and accurate frequency locks within a given frequency range. 42. The method of claim 41, further comprising the step of using multiple phase-lock-loop-controlled oscillator circuits to provide a broader range of frequency measurements during designated measurement periods. 43. The method of claim 41, wherein the identified parameters are the tuning/output voltage from the phase-lock-loop-controlled oscillator circuits when the frequency is locked, the forward voltage to the sensor and the reflected voltage from the sensor. 44. The method of claim 38, wherein the signal is a radio frequency signal. 45. The method of claim 38, wherein the signal is a microwave signal. 46. The method of claim 38, wherein the transmission lines are of substantially identical lengths. 47. A method for monitoring the concentration of individual components within a fluid mixture, comprising the following steps of: a) providing a sensor device comprising a microcontroller, a reference sensor and a measurement sensor mounted in a sensor housing, wherein the reference sensor and the measurement sensor include an electrode and a transmission line from a signal source, wherein the transmission lines are independently adjustable in length and an electronics instrument package in communication with the microcontroller, the electronics instrument package having a signal generating/receiving unit in communication with the measurement transmission line and the reference transmission line, wherein the signal/receiving unit reciprocably activates the measurement electrode and the reference electrode to measure a parameter of the fluid mixture at a predetermined frequency; b) exposing an electrode of at least one measurement sensor to the fluid mixture; c) shielding the reference sensor from the fluid mixture; d) providing identical exposure of at least one measurement sensor and the reference sensor to a pressure and a temperature of the fluid mixture; e) transmitting a signal to the reference sensor; f) receiving a reflected signal from the reference sensor; g) transmitting a signal to at least one measurement sensor; h) receiving a reflected signal from at least one measurement sensor; i) detecting the difference in the transmitted and reflected signals; j) using the detected differences to calculate the permittivities of the components of the fluid mixture; k) determining the concentration of individual components within the fluid mixture based on the calculated permittivities of the components; and l) repetitively sampling and processing the transmitted and reflected signals to produce a plurality of samples for real time monitoring of the concentration of individual components in the fluid mixture. 48. A sensor device for determining the concentration of fluid components within a fluid mixture comprising: a) a microcontroller; b) a sensor probe including: (i) a probe housing having a fluid passageway, such that when the probe housing is positioned in a fluid flow conduit a fluid mixture flowing through the flow conduit can pass through the fluid passageway in the probe housing, (ii) a reference sensor mounted within the probe housing, the reference sensor having a reference electrode in communication with a reference transmission line, wherein a portion of the reference electrode is covered by a reference isolator, and (iii) a measurement sensor mounted within the probe housing and coaxially offset from the reference sensor and the probe housing, the measurement sensor having a measurement electrode in communication with the fluid mixture and a measurement transmission line; and c) an electronics instrument package in communication with the microcontroller, the electronics instrument package having a signal generating/receiving unit in communication with the measurement transmission line and the reference transmission line, wherein the signal/receiving unit reciprocably activates the measurement electrode and the reference electrode to measure a predetermined parameter of the fluid mixture at a predetermined frequency, wherein the microcontroller calculates a compensation factor based on at least one measurement of the measured parameter by the reference sensor and a permittivity of a component of the fluid mixture based on multiple compensated measurements of the measured parameter by the measurement sensor; whereby the microcontroller determines the concentration of the component in the fluid mixture using the calculated permittivity. 49. A sensor device for determining the concentration of fluid components comprising: a) a microcontroller; b) an electronics package in communication with the microcontroller, wherein the electronics package has a signal generating/receiving unit, wherein the signal/generating unit includes a means for changing the generated signal at a predetermined rate, each generated signal selected from a set of predetermined signals; and c) a probe in communication with the electronics package, wherein the probe comprises: (i) a body having slots for receiving a fluid mixture, (ii) a reference sensor mounted within the body having a transmission line to the electronics instrument package, wherein the reference sensor has a reference electrode that is activated by the signal generating/receiving unit; and (iii) a measurement sensor mounted within the body axially offset from the probe body and the reference sensor, wherein the measurement sensor has a transmission line to the electronics instrument package and a measurement electrode activated by the signal generating/receiving unit to produce multiple measurements of selected parameters; d) wherein the signal/receiving unit reciprocably activates the measurement electrode and the reference electrode to measure a predetermined parameter of the fluid mixture at a predetermined frequency; and e) wherein the microcontroller compensates for anomalies in the measured parameters based on data acquired by the microcontroller from the reference sensor, calculates the permittivities of at least two individual fluid components based on the compensated measurements of the measurement sensor, and determines the concentration of the individual fluid components in the fluid mixture.