Venturi cluster, and burners and methods employing such cluster

Abstract

A burner arrangement includes a venturi cluster including a plurality of venturis arranged for parallel flow. The multi venturi arrangement utilizing pressurized fuel as the inducing fluid to induce a flow of air enables the provision of an ultra fuel lean premix of fuel and air. A central burner tube which extends outwardly beyond the delivery end of a primary burner tip and mounts a relatively small capacity nozzle at a substantial distance from the delivery end of the burner tip enabling the ultra fuel lean mixture to expand and slow down such that its linear speed does not exceed the flame speed of the mixture prior to by the flame of the spaced nozzle. A deflector may be positioned adjacent the nozzle to assist in stabilizing the flame after the expansion and slowing process has been completed.

1 . A method for increasing the capacity of a venturi device to induce the flow of an induced material into an inducing fluid when a flow of the inducing fluid is passed through the device, said method comprising: 
 separating said first fluid into at least two separate flow portions;    passing each separate flow portion of said first fluid through a respective venturi to independently induce a flow of said induced material into each of said flow portions thereby creating respective separate mixtures of said induced material and said inducing fluid; and    admixing the respective separate mixtures to thereby create an admixture of said inducing fluid and said induced material containing a greater concentration of said induced material than would be possible by passing the entire amount of said inducing fluid through a single venturi.    
   
   
       2 . A method as set forth in  claim 1 , wherein said inducing fluid is separated into at least three of said separate flow portions.  
   
   
       3 . A method as set forth in  claim 1 , wherein said inducing fluid is separated into at least six of said separate flow portions.  
   
   
       4 . A method as set forth in  claim 1 , wherein said inducing fluid is a gaseous fuel.  
   
   
       5 . A method as set forth in  claim 4 , wherein said induced material is air.  
   
   
       6 . A method for decreasing the length of a venturi device adapted for inducing the flow of an induced material into an inducing fluid when a flow of the inducing fluid is passed through the device, said method comprising: 
 separating said inducing fluid into at least two separate flow portions;    passing each separate flow portion of said inducing fluid through a respective venturi to independently induce a flow of said induced material into each of said flow portions thereby creating respective separate mixtures of said induced material and said inducing fluid; and    admixing the respective separate mixtures to thereby create an admixture of said induced material and said inducing fluid containing a greater concentration of said induced material than would be possible by passing the entire amount of said inducing fluid through a single venturi of the same length.    
   
   
       7 . A method for operating a venturi device comprising: 
 providing at least two venturis, each venturi having an inlet, a throat and an outlet, and each being operable for inducing the flow of an induced material when an inducing fluid is passed therethrough, whereby to produce a respective mixture of the induced material and the inducing fluid and discharging the mixture from the outlet thereof;    passing a first inducing fluid through a first of said venturis to thereby induce the flow of a first induced material and produce a first mixture comprising the first inducing fluid and the first induced material, and discharging said first mixture from the outlet of said first venturi;    passing a second inducing fluid through a second of said venturis to thereby induce the flow of a second induced material and produce a second mixture comprising the second inducing fluid and the second induced material, and discharging said second mixture from the outlet of said second venturi; and    collecting and intermixing said first and second mixtures to present a single mixed stream of said fluids and materials.    
   
   
       8 . A method for operating a burner equipped with a venturi device for supplying a combustible mixture to a burner nozzle, said method comprising: 
 providing at least two venturis, each venturi having an inlet, a throat and an outlet, and each being operable for inducing the flow of an induced fluid when an inducing fluid is passed therethrough, whereby to produce a respective mixture of the induced and inducing fluids and discharging the mixture from the outlet thereof;    passing a first inducing fluid through a first of said venturis to thereby induce the flow of a first induced fluid and produce a first mixture comprising the first inducing fluid and the first induced fluid, and discharging said first mixture from the outlet of said first venturi;    passing a second inducing fluid through a second of said venturis to thereby induce the flow of a second induced fluid and produce a second mixture comprising the second inducing fluid and the second induced fluid, and discharging said second mixture from the outlet of said second venturi; and    collecting and intermixing said first and second mixtures to present a single combustible mixed stream of said fluids.    
   
   
       9 . A method as set forth in  claim 8 , wherein said first and second inducing fluids are each gaseous fuels.  
   
   
       10 . A method as set forth in  claim 9 , wherein said first and second induced fluids are each air.  
   
   
       11 . A method as set forth in  claim 9 , wherein said first induced fluid is air and said second induced fluid is a recirculated flue gas.  
   
   
       12 . A method as set forth in  claim 8 , wherein one of said induced fluids is a diluent.  
   
   
       13 . A method as set forth in  claim 12 , wherein said diluent is steam.  
   
   
       14 . A method as set forth in  claim 12 , wherein said diluent is nitrogen.  
   
   
       15 . A method for operating a burner comprising: 
 delivering a flow of a combustible mixture comprising a fuel and air from a nozzle to a combustion zone at composition where the flame speed of the mixture is lower than the velocity of the mixture as the latter exits the nozzle;    allowing the mixture to expand and thereby slow to a velocity which is no greater than said flame speed; and    igniting said mixture only after said velocity which is no greater than said flame speed has been achieved.    
   
   
       16 . A method as set forth in  claim 15 , wherein said mixture is ultra fuel lean.  
   
   
       17 . A method as set forth in  claim 10 , wherein said single combustible mixed stream of said fluids is fuel lean and the same is delivered to a combustion zone at a velocity which exceeds the flame speed of the mixture, said method further comprising: 
 allowing the mixed stream to expand and thereby slow to a velocity which is no greater than said flame speed; and    igniting said mixed stream only after said velocity which is no greater than said flame speed has been achieved.    
   
   
       18 . A method as set forth in  claim 1 , wherein said material is a fluid.  
   
   
       19 . A method as set forth in  claim 1 , wherein said material is a flowable solid.  
   
   
       20 . A method as set forth in  claim 6 , wherein said material is a fluid.  
   
   
       21 . A method as set forth in  claim 6 , wherein said material is a flowable solid.  
   
   
       22 . A method as set forth in  claim 7 , wherein said material is a fluid.  
   
   
       23 . A method as set forth in  claim 7 , wherein said material is a flowable solid.