Monitoring of flames using optical fibers and video camera vision system

Abstract

This invention relates to a flame detection method and apparatus. More specifically, this invention relates to a flame d on method and apparatus designed for simultaneously monitoring several flames of different types such as pilot flames and main flames of differing sizes and intensity. These detected flames can be in one combustion unit or in several combustion units such as industrial furnaces or ground flares. The underlying principle of the invention is to collect and transmit light from each of the flames by use of optical fibers and to insect the collected light by a video camera vision system at the other end of the optical fibers and to transmit the “live” images of the glows as well as the “on/off” status of the burners to the control room, through modern electronic communication techniques such as Ethernet and/or wireless radio units.

1 . A method for monitoring the status of a combustion unit having at least one burner, comprising the steps of: 
 (a) Installing an optical fiber with tip its tip in or on the housing of the burner, collecting the light from the flame of the burner on the tip of the said optical fiber and transmitting said light to the tip of the other end of the said optical fiber.    (b) Acquiring a digital image of the glow at the end of the tip of the said optical fiber corresponding to the flame of the burner.    (c) Calculating a value for the relative intensity of the light in a frame defining an area of the image corresponding to the flame of the burner    (d) Comparing the relative intensity value against a tolerance range for the frame    (e) Generating an alarm state output if the relative intensity range is outside said tolerant range    
   
   
       2 . The method of the  claim 1  wherein the area of the frame is substantially less than a total area of the image  
   
   
       3 . The method of  claim 1  wherein a series of digital images are acquired at periodic time intervals and steps (c) through (e) are repeated for each digital image  
   
   
       4 . The method of  claim 3  wherein the periodic time intervals are regular and wherein each is less than one second.  
   
   
       5 . The method of  claim 1  further comprising of generating a display of the digital Image  
   
   
       6 . The method of  claim 5  further comprising operatively coupling said alarm state output with said display to superimpose an alarm state display over said image in the display.  
   
   
       7 . A method for monitoring the status of a combustion unit having at least one burner with a main burner flame and a pilot burner flame, comprising the steps of: 
 (a) Installing two optical fibers with their tips in or on the housing of the burner, one to collect the light from the said main flame and the other to collect the light from the said pilot flame and transmitting the said lights to the other ends of the fibers for the digital imaging of the two glows at the tips of the optical fibers.    (b) Acquiring a digital image of the two said glows corresponding to the main flame and the pilot flame.    (c) Calculating the values for the relative intensities of the frames defining the areas of the images corresponding to the two flames    (d) Comparing the relative intensity values against individual tolerance ranges for the two frames    (e) Generating an alarm state output if the relative light intensity value for each and any of the flames is outside its said tolerance range.    
   
   
       8 . The method of  claim 7  wherein a series of digital images are acquired at periodic time intervals and steps (c) through (e) are repeated for each digital image  
   
   
       9 . The method of  claim 8  wherein the periodic time intervals are regular and wherein each is less than one, second.  
   
   
       10 . A method for monitoring the status of a combustion unit having a plurality of burners, comprising the steps of: 
 (a) Installing optical fibers in or on the housing of every burner so that the tips of the fibers inside the burners view the flames of the said burners and collecting the light from the flames of the burners and transmitting the light to the other end of the fibers    (b) Acquiring a digital image of the glows at the far end of the tips of the optical fibers.    (c) Calculating the values for the relative intensities of the frames defining the areas of the images corresponding to the flames of the burners    (d) Comparing the relative intensity values against a tolerance range for each frame    (e) Generating an alarm state output if the relative light intensity value is outside said tolerance range.    
   
   
       11 . The method of  claim 10  wherein a series of digital images are acquired at periodic time intervals and steps (c) through (e) are repeated for each digital image  
   
   
       12 . The method of  claim 11  wherein the periodic time intervals are regular and wherein each is less than one second.  
   
   
       13 . A method for providing additional safety by having more than one fiber in each optical fiber bundle while monitoring the status of flames in a combustion unit with one or more burners, comprising the steps of: 
 (a) Making special optical fiber cables with two optical fibers in parallel inside every bundle.    (b) Installing such said special cables in or on the housing of every burner.    (c) Setting the parameter in the vision system to recognize “two-distinct glows” inside the frame designated for each specific flame.    (d) Programming the vision software to display “flame on” or “pass” if the image has at least one “glow” and to display “flame off” or “fail” if both the glows are absent.    (e) Generating an alarm state output if the specific flame has no “glows”    
   
   
       14 . A method for monitoring the status of several combustion units each having one or more burners, comprising the steps of: 
 (a) Installing optical fibers in every burner in all the said combustion units with their tips in or on the burners to view the flames of the said burners and collecting the lights from the flames on the tips of said optical fibers and transmitting the said lights to the tips at the other end of the fibers    (b) Acquiring digital images of the glows at the tips of the optical fibers corresponding to the flames of the burners    (c) Arranging the lights received in groups corresponding to each of the said combustion units from which they originated    (d) Calculating the values for the relative intensities of the frames in each said group defining the areas of the images corresponding to the flames of the burners    (e) Comparing the relative intensity values against a tolerance ranges for each of the frames.    (f) Generating an alarm state output if the relative light intensity value is outside said tolerance range.    
   
   
       15 . The method of  claim 14  wherein a series of digital images are acquired at periodic time intervals and steps (c) through (e) are repeated for each digital image  
   
   
       16 . The method of  claim 15  wherein the periodic time intervals are regular and wherein each is less than one second.  
   
   
       17 . Apparatus for monitoring the status of one or more combustion units having a plurality of burners, comprising: 
 Optical fibers with tips designed for easy installation in or on a burner housing at the light-receiving end and into a dark chamber box at the light-displaying end    A dark chamber box: All the light displaying ends of the said optical fibers will be installed on one end plate of this enclosure impervious to external light.    A machine vision camera will be installed at the other end of the said box for acquiring a digital image of the plurality of glows from the flames corresponding to the burners.    Special vision software on a computer: The special software enables analyzing the specific flame monitoring application and programming it into the camera system. The program is thus customized for each application as per its needs.    The said programmed software is capable of    (1) Calculating an array of light intensity values relative to a baseline light intensity value for a plurality of frames, each frame defining a sub-area of the digital image corresponding to the flame for one of the burners,    (2) Comparing the relative intensity values against a tolerance range for each frame, and    (3) Generating an alarm state output for each relative light intensity value that is outside the range    The data communication module: This module is capable of receiving and transmitting through the Ethernet the video images, the data of the on/off status of all the flames, other statistical data such as history of the monitored data, and the time of flame failure.    An Ethernet cable to physically connect the above referred communication module at the camera end to the below referred gateway module at the control room end.    A communications gateway module that can receive and send video images and data from several camera vision systems.    One or more video monitors in the control room to display the live images of the light glows from the flames of the burners, the on/off status on all the burners, and other statistical and-historical data on the performance status of the burners.    An alarm system activated by the alarm state output.    
   
   
       18 . The apparatus of  claim 17  for monitoring the status of one or more combustion units having a plurality of burners, wherein: 
 High speed Ethernet wireless radio transmitters and receivers are used instead of hard wire ethernet cable connection for communication between the camera and the control room.