Swirl-Stabilized Burner for Thermal Management of Exhaust System and Associated Method

Abstract

An apparatus comprises a reciprocating or Wankel engine, an exhaust gas passageway fluidly coupled to the engine, and a fuel-fired burner. The burner is positioned in the exhaust gas passageway and comprises a swirler configured to swirl exhaust gas of the engine so as to stabilize in the exhaust gas passageway a flame generated by the burner without use of supplemental combustion air when the engine is operating above idle. An associated method is disclosed.

1 . A method, comprising the steps of: 
 generating a flame in exhaust gas of a reciprocating or Wankel engine without use of supplemental combustion air,    swirling the exhaust gas while the engine is operating above idle, and    stabilizing the flame in the exhaust gas as a result of the swirling step.    
   
   
       2 . The method of  claim 1 , wherein: 
 the swirling step comprises (i) generating an outer swirl zone of swirling exhaust gas and (ii) generating within the outer swirl zone an inner recirculation zone of recirculating exhaust gas, and    the stabilizing step comprises stabilizing the flame in the inner recirculation zone.    
   
   
       3 . The method of  claim 1 , wherein: 
 the generating step comprises generating a pilot flame, and    the stabilizing step comprises stabilizing the pilot flame as a result of the swirling step.    
   
   
       4 . The method of  claim 3 , wherein: 
 the generating step comprises generating a main flame initiated by the pilot flame, and    the stabilizing step comprises stabilizing the main flame as a result of the swirling step.    
   
   
       5 . The method of  claim 1 , wherein: 
 the generating step comprises a generating a main flame initiated by a pilot flame, and    the stabilizing step comprises stabilizing the main flame as a result of the swirling step.    
   
   
       6 . The method of  claim 1 , wherein: 
 the generating step comprises generating a pilot flame in a perforated pilot tube, and    the swirling step comprises swirling exhaust gas with a swirler surrounding the pilot tube so as to cause exhaust gas to enter the pilot tube through apertures formed therein, further comprising the step of forming a wall-cooling layer of exhaust gas on an inner surface of the pilot tube with exhaust gas that has entered the pilot tube through the apertures formed therein.    
   
   
       7 . The method of  claim 1 , wherein the swirling step comprises varying a swirl number of the exhaust gas.  
   
   
       8 . The method of  claim 1 , wherein the swirling step comprises swirling exhaust gas in opposite directions around an axis.  
   
   
       9 . The method of  claim 1 , further comprising directing exhaust gas toward a fuel dispenser by use of vanes adjacent to and inclined toward one another and swirling the exhaust gas directed toward the fuel dispenser about fuel dispensed from the fuel dispenser, wherein the generating step comprises combusting the fuel dispensed from the fuel dispenser to generate a main flame.  
   
   
       10 . The method of  claim 1 , further comprising thermally managing an emission abatement device by use of the swirl-stabilized flame.  
   
   
       11 . An apparatus, comprising: 
 a reciprocating or Wankel engine,    an exhaust gas passageway fluidly coupled to the engine, and    a fuel-fired burner positioned in the exhaust gas passageway and comprising a first swirler configured to swirl exhaust gas of the engine so as to stabilize in the exhaust gas passageway a flame generated by the burner without use of supplemental combustion air when the engine is operating above idle.    
   
   
       12 . The apparatus of  claim 11 , wherein: 
 the burner comprises a pilot section configured to generate a pilot flame, and    the pilot section comprises a pilot fuel dispenser and the first swirler which is positioned about the pilot fuel dispenser for stabilizing the pilot flame.    
   
   
       13 . The apparatus of  claim 11 , wherein: 
 the burner comprises a pilot section and a main section,    the pilot section is configured to generate a pilot flame and the main section is configured to generate a main flame initiated by the pilot flame, and    the main section comprises the first swirler for stabilizing the main flame.    
   
   
       14 . The apparatus of  claim 11 , wherein: 
 the burner comprises a pilot section and a main section,    the pilot section is configured to generate a pilot flame and the main section is configured to generate a main flame initiated by the pilot flame,    the pilot section comprises (i) a pilot fuel dispenser, (ii) the first swirler which is positioned circumferentially about the pilot fuel dispenser for stabilizing the pilot flame, (iii) a perforated pilot tube that is configured to receive the pilot flame, and (iv) a second swirler positioned circumferentially about the perforated pilot tube for swirling exhaust gas to promote passage of exhaust gas through apertures defined in the perforated pilot tube, and    the main section comprises (i) a main fuel dispenser for dispensing fuel to be ignited at least initially by the pilot flame to generate the main flame and (ii) a third swirler configured to swirl exhaust gas so as to stabilize the main flame in the exhaust gas passageway.    
   
   
       15 . The apparatus of  claim 14 , further comprising a particulate filter and an oxidation catalyst for heating the particulate filter, wherein: 
 there is a fuel-dosing section for introducing fuel into the exhaust gas passageway upstream from the oxidation catalyst to promote operation of the oxidation catalyst,    the fuel-dosing section is included as part of the burner or is separate from the burner so as to be positioned downstream therefrom at a location between the burner and the oxidation catalyst, and    the fuel-dosing section comprises a fuel-dosing dispenser and a fourth swirler configured to swirl exhaust gas so as to mix exhaust gas and fuel dispensed by the fuel-dosing dispenser.    
   
   
       16 . The apparatus of  claim 11 , wherein the first swirler comprises at least one vane.  
   
   
       17 . The apparatus of  claim 16 , further comprising a pitch adjuster secured to the first swirler to adjust the pitch of the at least one vane.  
   
   
       18 . The apparatus of  claim 16 , wherein the at least one vane is formed such that the pitch of the at least one vane varies along the length of the at least one vane.  
   
   
       19 . The apparatus of  claim 11 , further comprising an emission abatement device, wherein the burner is positioned for thermal management of the emission abatement device by use of the swirl-stabilized flame.  
   
   
       20 . A method, comprising the steps of: 
 generating both a pilot flame and a main flame in exhaust gas of a reciprocating or Wankel engine without use of supplemental combustion air,    swirling the exhaust gas about an axis while the engine is operating above idle, and    stabilizing both the pilot flame and the main flame in the exhaust gas as a result of the swirling step.