Method and apparatus for determining gvf (gas volume fraction) for aerated fluids and liquids in flotation tanks, columns, drums, tubes, vats

Abstract

The invention provides a signal processor that receives a signal containing information about an acoustic signal that is generated by at least one acoustic transmitter, that travels through an aerated fluid in a container, and that is received by at least one acoustic receiver arranged in relation to the container, including inside the container; and determines the gas volume fraction of the aerated fluid based at least partly on the speed of sound measurement of the acoustic signal that travels through the aerated fluid in the container. The signal processor also sends an output signal containing information about the gas volume fraction of the aerated fluid. The signal processor may be configured together with at least one acoustic transmitter, the at least one acoustic receiver, or both.

What is claimed is: 
     
         1 . Apparatus comprising:
 a signal processor configured to:
 receive a signal containing information about an acoustic signal that is generated by at least one acoustic transmitter, that travels through an aerated fluid in a container, and that is received by at least one acoustic receiver arranged in relation to the container, including arranged inside the container; and 
 determine the gas volume fraction of the aerated fluid based at least partly on the speed of sound measurement of the acoustic signal that travels through the aerated fluid in the container. 
   
     
     
         2 . Apparatus according to  claim 1 , wherein the signal processor is configured to determine the speed of sound measurement based at least partly on a known separation distance between the at least one acoustic transmitter and the at least one acoustic receiver. 
     
     
         3 . Apparatus according to  claim 2 , wherein the signal processor is configured to determine the speed of sound measurement based at least partly on the at least one acoustic transmitter and the acoustic receiver probe being arranged at the same height in relation to the container. 
     
     
         4 . Apparatus according to  claim 1 , wherein the signal processor is configured to determine the speed of sound measurement based at least partly on the at least one acoustic transmitter emitting the acoustic signal at a frequency in a proper frequency range so that entrained air modifies the speed of sound in the aerated fluid. 
     
     
         5 . Apparatus according to  claim 1 , wherein the signal processor is configured to receive signals containing information about the acoustic signal that is received by two acoustic receiver arranged inside the container. 
     
     
         6 . Apparatus according to  claim 5 , wherein the signal processor is configured to determine the speed of sound measurement based at least partly on knowing the distance between the two acoustic receivers. 
     
     
         7 . Apparatus according to  claim 1 , wherein the signal processor is configured to record an elapsed time between pulse generation and detection. 
     
     
         8 . Apparatus according to  claim 1 , wherein the signal processor is configured to provide an output signal containing information about the gas volume fraction of the aerated fluid, that may be used to control the process, including information about providing a chemical additive to the aerated fluid in the container. 
     
     
         9 . Apparatus according to  claim 8 , wherein the process is a flotation process in mineral processing to aid in the separation of ore, including adding chemicals known as frothers to control the efficiency of the flotation process by enhancing the properties of air bubbles. 
     
     
         10 . Apparatus according to  claim 1 , wherein the process is a mixing process for making concrete, including mixing concrete in a ready mix truck or in a stationary concrete mixer box. 
     
     
         11 . Apparatus according to  claim 1 , wherein the process is a food process, including adding lysene for producing ice cream. 
     
     
         12 . Apparatus according to  claim 1 , wherein the process is a cosmetics process for producing make-up. 
     
     
         13 . Apparatus according to  claim 1 , wherein the process is a mixing process for producing paint or coating fluid. 
     
     
         14 . Apparatus according to  claim 1 , wherein the signal processor is configured to receive the signal containing information about acoustic signals generated by driving a piezoelectric material or a mechanical impulse. 
     
     
         15 . Apparatus according to  claim 1 , wherein the at least one acoustic transmitter is arranged on the outside of the container. 
     
     
         16 . Apparatus according to  claim 1 , wherein the at least one acoustic transmitter is arranged on the inside of the container. 
     
     
         17 . Apparatus according to  claim 1 , wherein the at least one acoustic transmitter is omnidirectional. 
     
     
         18 . Apparatus according to  claim 1 , wherein the container is a flotation column or tank. 
     
     
         19 . Apparatus according to  claim 1 , wherein apparatus comprises a device configured to receive the output signal, and also configured to add the chemical additive to the container in order to control the process related to the aerated fluid in a closed loop system. 
     
     
         20 . Apparatus according to  claim 1 , wherein the process is a mixing process for making concrete, including mixing concrete in a mobile concrete truck or in a stationary concrete mixer box. 
     
     
         21 . Apparatus according to  claim 1 , wherein the at least one acoustic transmitter and the at least one acoustic receiver take the form of a projector/receiver pair separated by a small distance and attached to a drum inspection hatch of a ready mix truck. 
     
     
         22 . Apparatus according to  claim 21 , wherein the projector/receiver pair is installed through the drum inspection hatch so as to be inside the cavity of a mixer drum of the ready mix truck. 
     
     
         23 . Apparatus according to  claim 21 , wherein the drum inspection hatch is configured to form a cavity and the projector/receiver pair is installed in the cavity and exposed to the concrete inside a mixer drum. 
     
     
         24 . Apparatus according to  claim 21 , wherein the apparatus comprises a wireless transmitter configured to provide a wireless signal containing information about an air content value of the concrete, including to a local display and/or communications module on the mixer truck. 
     
     
         25 . Apparatus according to  claim 1 , wherein the at least one acoustic transmitter and acoustic receiver take the form of a projector/receiver pair separated by a small distance and mounted on a chute that is used to pour concrete for continuously measuring the concrete being poured. 
     
     
         26 . Apparatus according to  claim 1 , wherein the signal processor is configured to receive signals containing information about the acoustic signal that is generated by the at least one acoustic transmitter, that travels through the aerated fluid in the container, and that is received by an array of acoustic receivers. 
     
     
         27 . Apparatus according to  claim 26 , wherein the signal processor is configured to determine the gas volume fraction of the aerated fluid based at least partly on multipath interrogation of each measurement point, where each acoustic receiver can be used to detect a respective signal from each acoustic transmitter. 
     
     
         28 . Apparatus according to  claim 1 , wherein the signal processor is configured to receive signals containing information about acoustic signals that are generated by an array of acoustic transmitters, that travel through the aerated fluid in the container, and that are received by an array of acoustic receivers. 
     
     
         29 . Apparatus according to  claim 28 , wherein the signal processor is configured to determine the gas volume fraction of the aerated fluid based at least partly on multipath interrogation of each measurement point, where each acoustic receiver can be used to detect a respective signal from each acoustic transmitter. 
     
     
         30 . Apparatus according to  claim 28 , wherein the signal processor is configured to receive signals containing information about the acoustic signals that are generated by the array of acoustic transmitters having each acoustic transmitter selectively encoded with a different frequency, slice of spectrum, chirp/modulation characteristic allowing each channel to be individually analyzed, that travel through the aerated fluid in the container, and that are received by an array of acoustic receivers. 
     
     
         31 . Apparatus according to  claim 28 , wherein the signal processor is configured to receive signals containing information about the acoustic signals that are generated by the array of acoustic transmitters energized with pseudo noise sources so delay-correlation techniques can be used to detect the transmit time for each transmitter-to-receiver path, that travel through the aerated fluid in the container, and that are received by an array of acoustic receivers. 
     
     
         32 . Apparatus according to  claim 1 , wherein the at least one acoustic transmitter arranged on the outside of the container operates through the wall of the container. 
     
     
         33 . Apparatus according to  claim 32 , wherein the at least one acoustic transmitter is inserted in a port in the wall that allows contact with the aerated fluid. 
     
     
         34 . Apparatus according to  claim 33 , wherein the at least one acoustic transmitter is configured to generate low frequency acoustics by driving a diaphragm, including by pressure or mechanical/electrical excitation, used to propagate a sound signal into the aerated fluid. 
     
     
         35 . Apparatus according to  claim 1 , wherein the apparatus further comprises the at least one acoustic transmitter that is arranged in relation to the container having aerated fluid therein and configured to generate the acoustic signal that travels through the aerated fluid. 
     
     
         36 . Apparatus according to  claim 1 , wherein the apparatus further comprises the at least one acoustic receiver that is arranged in the container and configured to receive the acoustic signal and provide the signal containing information about the acoustic signal generated by the at least one acoustic transmitter. 
     
     
         37 . A method comprising:
 receiving a signal containing information about an acoustic signal that is generated by at least one acoustic transmitter, that travels through an aerated fluid in a container, and that is received by at least one acoustic receiver arranged in relation to the container, including inside the container; and   determining the gas volume fraction of the aerated fluid based at least partly on the speed of sound measurement of the acoustic signal that travels through the aerated fluid in the container.   
     
     
         38 . A method according to  claim 37 , wherein the method comprises providing an output signal containing information about the gas volume fraction of the aerated fluid, that may be used to control the process, including information about providing a chemical additive to the aerated fluid in the container. 
     
     
         39 . Apparatus comprising:
 means for receiving a signal containing information about an acoustic signal that is generated by at least one acoustic transmitter, that travels through an aerated fluid in a container, and that is received by at least one acoustic receiver arranged in relation to the container, including inside the container; and   means for determining the gas volume fraction of the aerated fluid based at least partly on the speed of sound measurement of the acoustic signal that travels through the aerated fluid in the container.