Particle tracking technique for studying fluid flow in industrial vessels

Abstract

An apparatus and method for determining the position of an object, especially the position of a movable object in an industrial vessel. The position is determined by the use of two signals having a very large difference in their velocities, such as electromagnetic and acoustic waves. The object whose position is to be determined receives the electromagnetic signal, analyzes the electromagnetic signal, and, if appropriate, transmits an acoustic signal. In addition to the object containing an electromagnetic receiver and an acoustic transmitter, there is required an electromagnetic transmitter, three or more receivers to receive the acoustic signal from the object, and supporting equipment to process signals and log data. When the object transmits an acoustic signal, the acoustic receivers, which are in known positions in the vessel, receive the signal at different times depending on the distance of the object from each receiver. From the speed of the acoustic signal in the medium contained in the vessel and the time required for the signal to reach each receiver, the distances from each receiver to the object are calculated. Because the location of each receiver is known, it is possible by triangulation to calculate the position of the object.

What is claimed is: 
     
       1. An apparatus for locating a position of a movable object within a coordinate system comprising: (a) a first transmitting means for transmitting an electromagnetic signal at a first velocity;   (b) a transceiver element for receiving the electromagnetic signal, analyzing the electromagnetic signal, and transmitting an acoustic signal at a second velocity in response to the electromagnetic signal;   (c) a transducer for receiving the acoustic signal and for generating a third signal in response to receiving the acoustic signal;   (d) a signal processor for receiving the third signal and calculating the elapsed time between the transmission of the electromagnetic signal and the receipt of the acoustic signal; and   (e) a control device for controlling the first transmitting means and the signal processor, and for generating information from which the position of the object can be determined.   
     
     
       2. An apparatus according to claim 1, wherein the first velocity is very much greater than the second velocity. 
     
     
       3. An apparatus according to claim 1, including a plurality of transducers for receiving the acoustic signal, wherein each transducer generates a respective third signal. 
     
     
       4. An apparatus according to claim 1, wherein the acoustic signal is transmitted in a pulse mode. 
     
     
       5. An apparatus according to claim 1, wherein the movable object is disposed in a fluid in a vessel, in order to infer macroscopic fluid flow patterns from the sequential positions of the movable object. 
     
     
       6. An apparatus according to claim 5, wherein the movable object is free to move under the influence of fluid forces. 
     
     
       7. An apparatus according to claim 5, wherein one of the vessel and fluid is opaque. 
     
     
       8. An apparatus according to claim 5, wherein a process taking place in the vessel requires the absence of light. 
     
     
       9. An apparatus according to claim 1, wherein the movable object has a characteristic length on the order of one to three centimeters. 
     
     
       10. An apparatus accord to claim 1, wherein the acoustic signal has a frequency of about 10 6  hertz. 
     
     
       11. A method of obtaining information from which a location of a movable object in a coordinate system can be determined comprising: (a) transmitting an electromagnetic signal with a first transmitting means at a first velocity;   (b) receiving the electromagnetic signal with a transceiver, analyzing the electromagnetic signal, and transmitting an acoustic signal at a second velocity in response to the electromagnetic signal;   (c) receiving the acoustic signal with a transducer and generating a third signal in response to the acoustic signal;   (d) receiving the third signal with a signal processor and calculating the elapsed time between the transmission of the electromagnetic signal and the receipt of the acoustic signal; and   (e) controlling the first transmitting means and the signal processor with a control device, and generating information from which the position of the object can be determined.   
     
     
       12. A method as claimed in claim 11, further comprising an initial step of placing the transceiver on the movable object. 
     
     
       13. A method as claimed in claim 12, wherein the initial step of placing the transceiver on the movable object includes the step of placing the movable object in a fluid in a vessel, in order to infer macroscopic fluid flow patterns from the sequential positions of the movable object. 
     
     
       14. A method as claimed in claim 13, wherein the step of placing the movable object in a fluid in a vessel includes the step of placing the movable object in a fluid in a vessel wherein the movable object is free to move under the influence of fluid forces. 
     
     
       15. A method as claimed in claim 13, wherein the step of placing the movable object in a fluid in a vessel includes the step of placing the movable object in a fluid in a vessel wherein one of the vessel and fluid is opaque. 
     
     
       16. A method as claimed in claim 13, wherein the step of placing the movable object in a fluid in a vessel includes the step of placing the movable object in a fluid in a vessel wherein a process taking place in the vessel requires the absence of light. 
     
     
       17. A method as claimed in claim 12, wherein the initial step of placing the transceiver on the movable object includes the step of placing the transceiver on the movable object, said movable object having a characteristic length on the order of one to three centimeters. 
     
     
       18. A method as claimed in claim 11, wherein the step of receiving the acoustic signal includes receiving the acoustic signal with a plurality of transducers, each transducer generating a respective third signal. 
     
     
       19. A method as claimed in claim 11, wherein the step of transmitting an acoustic signal includes transmitting an acoustic signal in pulse mode. 
     
     
       20. A method as claimed in claim 11, wherein the step of transmitting an acoustic signal includes the step of transmitting an acoustic signal having a frequency of about 10 6  hertz.