Systems, methods and apparatus for non-disruptive and non-destructive inspection of metallurgical furnaces and similar vessels

Abstract

Some embodiments of the present invention provide systems, methods and apparatus for more accurately determining the thickness of a refractory lining included in an operating metallurgical furnace. Specifically, in some embodiments a transient propagated stress wave is used to determine the condition of a refractory lining, and additionally, provide a systematic way to include the affect that temperature has on the velocity of a compressive wave through a heated refractory material and/or accretions. As identified in aspects of the present invention, and contrary to the common understanding in the art, the velocity of a stress wave, at each frequency and in a refractory material, is not necessarily constant over a temperature range. In accordance with aspects of some specific embodiments of the invention, a scaling factor a can be calculated for each refractory material to adjust for the presumed velocity of the stress wave through each refractory material.

1 . A system for inspecting a metallurgical furnace wall comprising: 
 a stress wave generator for generating a stress wave that propagates into a metallurgical furnace wall;    a stress wave sensor for sensing reflections of the stress wave; and    a processor having computer readable program code means embodied thereon for (i) recording time domain data about the reflections of the stress wave sensed by the stress wave sensor, (ii) converting the time domain data into frequency domain data, and (iii) producing a determination of the condition of the metallurgical furnace wall by combining time domain data, the frequency domain data and a temperature-dependent scaling factor which compensates for the change in velocity of the stress wave and the reflections of the stress wave through a refractory material included in the metallurgical furnace wall.    
   
   
       2 . A system according to  claim 1 , wherein the temperature-dependent scaling factor is calculated as a function of a relative change in the modulus of elasticity over a temperature range corresponding to a temperature gradient through the refractory material within an operating metallurgical furnace.  
   
   
       3 . A system according to  claim 1 , wherein producing the determination of the condition of the metallurgical furnace wall includes determining the thickness of the metallurgical furnace wall.  
   
   
       4 . A system according to  claim 1 , wherein producing the determination of the condition of the metallurgical furnace wall includes determining the thickness of a refractory lining in the metallurgical furnace wall.  
   
   
       5 . A system according to  claim 1 , wherein producing the determination of the condition of the metallurgical furnace wall includes determining the presence or absence of defects including delaminations, accretions, cracks and bubbles.  
   
   
       6 . A system according to  claim 5 , wherein producing the determination of the condition of the metallurgical furnace wall also includes determining the position of defects including delaminations, accretions, cracks and bubbles.  
   
   
       7 . A system according to  claim 1 , wherein the stress wave is a compressive P-wave.  
   
   
       8 . A system according to  claim 1 , wherein the stress wave sensor is one of a vertical displacement transducer and an accelerometer.  
   
   
       9 . A system according to  claim 1 , wherein the stress wave generator is an impactor having a spherical impact point.  
   
   
       10 . A system according to  claim 1  further comprising a pre-amplifier coupled between the stress wave sensor and the processor.  
   
   
       11 . A system according to  claim 1 , wherein the processor further comprises computer readable program code means embodied thereon for including a geometry-dependent velocity scaling-factor in the determination of the condition of the metallurgical furnace wall.  
   
   
       12 . A system according to  claim 11 , wherein the refractory material included in the metallurgical furnace is provided in brick form, and the geometry-dependent scaling factor is calculated as a function of the relative dimensions of the refractory bricks.  
   
   
       13 . A system according to  claim 1 , wherein the metallurgical furnace wall under inspection is known to include a refractory lining having a plurality of layers, each composed of one type of refractory material, and wherein the processor further includes computer readable program code means embodied thereon for producing a determination of the condition the metallurgical furnace wall using a plurality of temperature-dependent scaling factors, each temperature-dependent scaling factor corresponding to a respective one type of refractory material in the refractory lining.  
   
   
       14 . A system according to  claim 13 , wherein each of the plurality of temperature-dependent scaling factors is calculated as a function of a relative change in the modulus of elasticity over a temperature range corresponding to a temperature gradient through the corresponding refractory material.  
   
   
       15 . A system according to  claim 13 , wherein the processor further comprises computer readable program code means embodied thereon for including a geometry-dependent velocity scaling-factor in the determination of the condition of the metallurgical furnace wall.  
   
   
       16 . A system according to  claim 15 , wherein each layer of the refractory lining is known to include refractory bricks of one type of refractory material and each of the plurality of geometry-dependent scaling factors is calculated as a function of the relative dimensions of the refractory bricks in a respective layer.  
   
   
       17 . An apparatus for inspecting a metallurgical furnace wall comprising: 
 a plurality of stress wave generator-sensor pairs, each pair for generating a stress wave and sensing reflections of the stress wave at point on a metallurgical furnace; and    a processor having computer readable program code means embodied thereon for producing a determination of the condition of the metallurgical furnace wall from a combination of time domain data collected by at least one sensor, frequency domain data derived from the time domain data, and a temperature-dependent scaling factor to correct for the change in velocity of the stress wave and the reflections of the stress wave through a refractory material included in the metallurgical furnace wall.    
   
   
       18 . An apparatus according to  claim 17 , wherein the temperature-dependent scaling factor is calculated as a function of a relative change in the modulus of elasticity over a temperature range corresponding to a temperature gradient through the refractory material within an operating metallurgical.  
   
   
       19 . An apparatus according to  claim 17 , wherein the determination of the condition of the metallurgical furnace wall includes determining the thickness of the metallurgical furnace wall.  
   
   
       20 . An apparatus according to  claim 17 , wherein the determination of the condition of the metallurgical furnace wall includes determining the thickness of a refractory lining in the metallurgical furnace wall.  
   
   
       21 . A system according to  claim 1 , wherein the determination of the condition of the metallurgical furnace wall includes determining the presence or absence of defects including delaminations, accretions, cracks and bubbles.  
   
   
       22 . An apparatus according to  claim 21 , wherein the determination of the condition of the metallurgical furnace wall also includes determining the position of defects including delaminations, accretions, cracks and bubbles.  
   
   
       23 . An apparatus according to  claim 17  further comprising a respective plurality of pre-amplifiers coupled between the plurality of stress wave generator-sensor pairs and the processor.  
   
   
       24 . An apparatus according to  17  further comprising a stress wave generator control box coupled between the processor and the plurality of stress wave generator-sensor pairs.  
   
   
       25 . An apparatus according to  claim 17 , wherein the processor further comprises computer readable program code means embodied thereon for including a geometry-dependent velocity scaling-factor in the determination of the condition of the metallurgical furnace wall.  
   
   
       26 . An apparatus according to  claim 25 , wherein the refractory material included in the metallurgical furnace is provided in brick form, and the geometry-dependent scaling factor is calculated as a function of the relative dimensions of the refractory bricks.  
   
   
       27 . An apparatus according to  claim 17 , wherein the metallurgical furnace wall under inspection is known to include a refractory lining having a plurality of layers, each composed of one type of refractory material, and wherein the processor further includes computer readable program code means embodied thereon for producing a determination of the condition of the metallurgical furnace wall using a plurality of temperature-dependent scaling factors, each temperature-dependent scaling factor corresponding to a respective one type of refractory material in the refractory lining.  
   
   
       28 . An apparatus according to  claim 27 , wherein each of the plurality of temperature-dependent scaling factors is calculated as a function of a relative change in the modulus of elasticity over a temperature range corresponding to a temperature gradient through the corresponding refractory material.  
   
   
       29 . An apparatus according to  claim 27 , wherein the processor further comprises computer readable program code means embodied thereon for including a geometry-dependent velocity scaling-factor in the determination of the condition of the metallurgical furnace wall.  
   
   
       30 . An apparatus according to  claim 29 , wherein each layer of the refractory lining is known to include refractory bricks of one type of refractory material and each of the plurality of geometry-dependent scaling factors is calculated as a function of the relative dimensions of the refractory bricks in a respective layer.  
   
   
       31 . A method of inspecting a metallurgical furnace wall comprising: 
 introducing a stress wave into a metallurgical furnace wall at a point;    sensing one or more reflections of the stress wave near the point of introduction of the stress wave into the metallurgical furnace wall; and    processing the reflections in the time and frequency domain in combination with a temperature-dependent scaling factor to correct for the change in velocity of the stress wave and the reflections of the stress wave through a refractory material included in the metallurgical furnace wall.    
   
   
       32 . A method according to  claim 31 , wherein the temperature-dependent scaling factor is calculated as a function of a relative change in the modulus of elasticity over a temperature range corresponding to a temperature gradient through the refractory material within an operating metallurgical furnace.  
   
   
       33 . A method according to  claim 31  further comprising determining the thickness of the metallurgical furnace wall.  
   
   
       34 . A method according to  claim 31  further comprising determining the thickness of a refractory lining in the metallurgical furnace wall.  
   
   
       35 . A method according to  claim 31  further comprising determining the presence or absence of defects including delaminations, accretions, cracks and bubbles.  
   
   
       36 . A system according to  claim 35  further comprising determining the position of defects present in the metallurgical furnace wall.  
   
   
       37 . A method according to  claim 31  further comprising amplifying sensed reflections before processing.  
   
   
       38 . A method according to  claim 31  further comprising including a geometry-dependent velocity scaling-factor in the determination of the condition of the metallurgical furnace wall.