ACTIVE ACOUSTIC SPECTROSCOPY

• US 20150059442A1
• Filed: 10/27/2014
• Published: 03/05/2015
• Est. Priority Date: 07/14/2000
• Status: Active Grant

• Current Assignee: Acosense AB
• Original Assignee: Acosense AB
• Inventors: Liljenberg, Thomas, Thegel, Lennart, Backa, Stevan, bom, Mats
• Granted Patent: US 9,772,311 B2
• Time in Patent Office: Days
• US Class Current: 73/24.01
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/0222 Binary liquids
• CPC Class Codes: G01N 2291/02416 Solids in liquids
• CPC Class Codes: G01N 2291/02433 Gases in liquids, e.g. bubbles, foams
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level
• CPC Class Codes: G01N 2291/02872 Pressure
• CPC Class Codes: G01N 29/032 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14

Abstract

In the present invention a controllable acoustic source (14) in connection with the process fluid (10) emits a signal (18) into the fluid (10), consisting of a suspension of particles (12), being volumes of gas, liquid or solid phase. The controllable acoustic signal (18) is allowed to interact, with the particles (12), and the acoustic (pressure) signals (22) resulting from such an interaction is measured preferably via a sensor (24). A spectrum is measured. The spectrum is used to predict properties, content and/or size of the particles (12) and/or used to control a process in which the process fluid (10) participates. The prediction is performed in the view of the control of the acoustic source (14). The used acoustic signal has preferably a frequency below 20 kHz.

Claims

1. An analyzing apparatus for analysis of a process fluid comprising a suspension of volumes of gas, liquid or solid phase, wherein the volumes have a phase different than a phase of the process fluid, said apparatus comprising:

an acoustic signal source operative to emit a controllable acoustic signal into said process fluid for interaction with said volumes of gas, liquid or solid phase, said acoustic signal comprising audible frequencies below 20 kHz and a wavelength that is larger than the volumes of gas, liquid or solid phase;

an acoustic signal sensor operative to measure acoustic signals from said process fluid and operative to measure a spectrum of acoustic signals resulting from said interaction of said controllable acoustic signal and said volumes of gas, liquid or solid phase, said spectrum comprising audible frequencies below 20 kHz, wherein the sensor and the signal source are not arranged in the path of the process fluid;

a processor connected to said acoustic signal sensor, said processor being configured to utilize multivariate statistical analysis of said measured spectrum of acoustic signals to determine at least one property influencing said interaction with said volumes of gas, liquid or solid phase,

wherein the analysis is based on a calibration with a known process fluid with known properties.

2. The apparatus according to claim 1, wherein said acoustic signal sensor is smaller than the wave length of waves emitted by said acoustic signal source.

3. The apparatus according to claim 1, wherein the processor comprises a module configured to carry out multivariate statistical analysis of said measured acoustic signals.

4. The apparatus according to claim 1, further comprising:

at least one additional acoustic signal sensor at another position in connection with said process fluid, connected to said processor.

5. The apparatus according to claim 4, comprising at least two acoustic signal sensors, wherein the two acoustic signal sensors are separated in a direction substantially along a flow path of the process fluid by a distance smaller than a wavelength of the acoustic signal emitted by the acoustic signal source.

6. The apparatus according to claim 4, comprising at least two acoustic signal sensors separated substantially perpendicularly to a flow path for said process fluid.

7. The apparatus according to claim 4, wherein said processor further comprises a module configured to decompose said measured acoustic signals into different propagating acoustic modes.

8. The apparatus according to claim 1, wherein at least one acoustic signal sensor is an acoustic pressure or a motion sensor.

9. The apparatus according to claim 1, wherein at least one acoustic signal sensor is attached on the outside of an enclosure of said process fluid.

10. The apparatus according to claim 1, wherein the property is the concentration of the volumes in the process fluid.

11. The apparatus according to claim 1, wherein the property is size distribution of the volumes in the process fluid.

12. The apparatus according to claim 1, wherein the property is average size of the volumes.

13. The apparatus according to claim 1, wherein the analyzing apparatus is adapted for analysis of a solid phase volume in a liquid process fluid.

14. An analyzing apparatus for analysis of a process fluid comprising a suspension of volumes of gas, liquid or solid phase, wherein the volumes have a phase different than a phase of the process fluid, said apparatus comprising:

an acoustic signal source operative to emit a controllable acoustic signal into said process fluid for interaction with said volumes of gas, liquid or solid phase, said acoustic signal comprising audible frequencies below 20 kHz and a wavelength that is larger than the volumes of gas, liquid or solid phase;

an acoustic signal sensor operative to measure acoustic signals from said process fluid and operative to measure a spectrum of acoustic signals resulting from said interaction of said controllable acoustic signal and said volumes of gas, liquid or solid phase, said spectrum comprising audible frequencies below 20 kHz, wherein the sensor and the signal source are not arranged in the path of the process fluid;

processing circuitry connected to said acoustic signal sensor and to said acoustic signal source, said processing circuitry being configured to;

control said acoustic signal source to emit said acoustic signal in the form of an amplitude modulated emitted acoustic signal;

acquire sensed acoustic signals from said acoustic signal sensor;

compare amplitude variations of said modulated emitted acoustic signal and said sensed acoustic signals to perform background reduction; and

utilize multivariate statistical analysis of said measured spectrum of acoustic signals to determine at least one property influencing said interaction with said volumes of gas, liquid or solid phase,

wherein said multivariate statistical analysis is based on a calibration with a known process fluid with known properties.

15. The analyzing apparatus according to claim 14 wherein said at least property is selected from the group comprising:

concentration of the volumes in the process fluid;

size distribution of the volumes in the process fluid; and

average size of the volumes in the process fluid.

16. An analyzing apparatus for predicting a value of a property of a process fluid flowing through a pipe, said analyzing apparatus comprising:

an acoustic signal source arranged at a source attachment location on an outside of said pipe and operative to emit an acoustic multi-frequency transmit signal into said process fluid, said acoustic transmit signal comprising audible frequencies below 20 kHz;

at least a first acoustic signal sensor arranged at a first sensor attachment location on the outside of said pipe and operative to acquire a first spectrum of acoustic signals resulting from interaction between said acoustic transmit signal and said process fluid;

a memory containing calibration data based on multivariate statistical analysis of previously acquired spectra of acoustic signals and corresponding values of said property based on measurements performed on said process fluid using a non-acoustic method; and

a processor connected to said first acoustic signal sensor and to said memory, and configured to provide a prediction of said value of the property based on said first spectrum of acoustic signals acquired by said first acoustic signal sensor and said calibration data.

17. The analyzing apparatus according to claim 16, further comprising a second acoustic signal sensor arranged at a second sensor attachment location on the outside of said pipe and operative to acquire a second spectrum of acoustic signals resulting from interaction between said acoustic transmit signal and said process fluid,

wherein said calibration data is based on multivariate statistical analysis of previously acquired combinations of first and second spectra of acoustic signals and corresponding values of said property based on measurements performed on said process fluid using a non-acoustic method, and

wherein said processor is further connected to said second acoustic signal sensor and configured to form a combined spectrum based on a combination of first and second spectra, and configured to provide a prediction of said value of the property based on a combination of said first spectrum and said second spectrum of acoustic signals, and said calibration data.

18. The analyzing apparatus according to claim 16, wherein said property of the process fluid is selected from the group comprising particle concentration, viscosity, specific surface area, and dry substance content.