Apparatus and method for determining fluid depth

Abstract

A fluid depth determination system is provided for a vessel that contains first and second immiscible fluids, where the second fluid floats on top of the first fluid forming an interface therebetween. The system includes a first pressure probe which is located in the floor of the vessel, a second pressure probe being at least vertically moveable in the first and second fluids in a region of the interface, means for collecting pressure readings from the first and second pressure probes and means for calculating the depth of the first fluid based on a difference in the pressure readings. The present invention is also directed to a method of determining a depth of a first fluid having an immiscible second fluid floating on top of the first fluid and forming an interface therebetween.

1 . A fluid depth determination system comprising a vessel having a floor and side walls for containing first and second immiscible fluids, wherein the first fluid has a bottom resting on the floor of the vessel and the second fluid floats on top of the first fluid fonming an interface therebetween, 
 a first pressure probe situated adjacent the floor of the vessel and the bottom of the first fluid,    a second pressure probe being at least vertically moveable in the first and second fluids in a region of the interface,    means for collecting pressure readings from the first and second pressure probes, and    means for calculating the depth of the first fluid by determining a difference in a pressure reading of the second probe and a pressure reading of the first probe.    
   
   
       2 . A system according to  claim 1 , wherein the vessel comprises a metallurgical vessel, the first fluid comprises molten metal, and the second fluid comprises slag.  
   
   
       3 . A system according to  claim 2 , wherein the metallurgical vessel is selected from the group consisting of metallurgical ladles, basic oxygen furnaces, argon-oxygen decarburization vessels, and tundish operation vessels.  
   
   
       4 . A system according to  claim 1 , wherein at least one of the first and second pressure probes comprises at least one orifice for emitting gas bubbles, a source of gas supplying a gas flow to the orifice, and a means for measuring pressure of the gas flow as it forms bubbles at the orifice.  
   
   
       5 . A system according to  claim 4 , wherein both the first and second pressure probes have at least one orifice for emitting gas bubbles, a source of gas supplying a gas flow to the orifice, and a means for measuring pressure of the gas flow as bubbles form at the orifice.  
   
   
       6 . A system according to  claim 4 , wherein the at least one orifice of the first pressure probe comprises at least one orifice located in the floor of the vessel.  
   
   
       7 . A system according to  claim 4 , wherein the at least one orifice of the second pressure probe is found at an end of at least one tube which is immersable in the first and second fluids.  
   
   
       8 . A system according to  claim 5 , wherein the first and second pressure probes have a common gas source.  
   
   
       9 . A system according to  claim 5 , wherein the first pressure probe comprises three orifices for emitting gas bubbles, a source of gas supplying a gas flow to the orifice, and a means for measuring the pressure of the gas flow, wherein the three orifices are found wherein the threes orifices are each found at an end of a tube and the tubes are substantially next to each other and are embedded in the floor of the vessel in a substantially vertical position so that the three orifices are substantially flush with the floor of the vessel.  
   
   
       10 . A system according to  claim 6 , wherein the at least one orifice is formed at the end of at least one tube through the floor of the vessel.  
   
   
       11 . A system according to  claim 10 , wherein the at least one tube is erodable with the floor of the vessel such that the at least one orifice remains located in the floor.  
   
   
       12 . A method of determining the depth of a first fluid having an immiscible second fluid floating on top of the first fluid and forming an interface therebetween, the method comprising 
 measuring a first pressure at a height adjacent a bottom of the first fluid,    measuring a second pressure at a height of the interface between the first and second fluids, and    calculating the depth of the first fluid based on the difference in the first and second pressures and using a formula:        h=P/ρg   (I)    wherein P=pressure, ρ=density of the fluid, g=acceleration due to gravity, and h=depth of fluid.    
   
   
       13 . The method according to  claim 12 , wherein the calculating step comprises subtracting the second pressure from the first pressure and applying the formula (I) to the difference obtained.  
   
   
       14 . The method according to  claim 12 , wherein at least one of the first and second pressure measuring steps comprises emitting at least one gas bubble at the height of the measurement and measuring a pressure of a gas flow which forms the bubble.  
   
   
       15 . The method according to  claim 12 , wherein the steps of measuring the second pressure comprises immersing a second pressure probe in the first fluid below the interface, withdrawing the second pressure probe from the first fluid at a predetermined speed, recording the pressures of the first and second fluids as the second pressure probe crosses the interface, and determining, a change in gradient.  
   
   
       16 . The method according to  claim 12 , wherein the first fluid and second fluid are contained in a vessel having sidewalls and a floor wherein the floor erodes and the first pressure is measured where the bottom of the first fluid and the floor of the vessel are in contact.  
   
   
       17 . The method according to  claim 12 , wherein both the first and second pressure probes have an orifice for emitting gas bubbles, a source of gas supplying flow to the orifice, wherein a back pressure is created from the fluid in the orifice and the back pressure is what is measured.  
   
   
       18 . The method according to  claim 14 , wherein the at least one measuring step measures the pressure of the gas which is just necessary to overcome the back pressure of the fluid.  
   
   
       19 . A fluid depth determination system comprising a vessel having a floor and sidewalls for containing first and second immiscible fluids, wherein the first fluid has a bottom resting on the floor of the vessel and the second fluid floats on top of the first fluid forming an interface therebetween, 
 a first pressure probe comprises at least one orifice located in the floor of the vessel, wherein the at least one orifice is located at the end of at least one tube and the at least one tube is erodable with the floor of the vessel such that the at least one orifice remains located in the floor,    a second pressure probe being at least vertically moveable in the first and second fluids in a region of the interface,    means for measuring pressure readings;    a gas source; and    a means for calculating, the depth of the first fluid based on a difference in the pressure readings.    
   
   
       20 . A method of determining a depth of a first fluid having, an immiscible second fluid floating on top of the first fluid and forming an interface therebetween, the method comprising, 
 measuring a first pressure at a height adjacent a bottom of the first fluid,    wherein the first pressure is a measurement of a back pressure necessary to overcome a back pressure of the fluid,    measuring the second pressure at a height of interface between the first and second fluids comprising 
 immersing a second pressure probe in the first fluid below the interface,  
 withdrawing the second pressure from the first fluid at a predetermined speed,  
 analyzing the pressures of the first and second fluids as the second pressure probe crosses the interface and  
 determining where a greatest change in pressure occurs;  
   wherein the second pressure is a measurement of a pressure necessary to overcome a back pressure of the fluid,    calculating the depth of the first fluid based on the difference in the first and second pressures using the formula:        h=P/ρg   (I)    wherein P=pressure, ρ=density of the fluid, g=acceleration due to gravity and h=depth of the fluid.