Combustion method and burner head, burner comprising one such burner head, and boiler comprising one such burner head

Abstract

A burner head has at least two and preferably four openings ( 45 ) in an aperture plate ( 37 ), with uniformly inclined guide blades ( 23 ) for the delivery of incoming air in the direction of an axis ( 31 ) to a combustion chamber ( 15 ) in the form of incoming air jets ( 53 ) intersecting one another in the chamber. Between the openings ( 45 ), blocking blades ( 27 ) are embodied, for forming peripheral underpressure zones ( 55 ) between the incoming air jets ( 53 ). The incoming air jets ( 53 ) are deflected by the guide blades ( 23 ) into a position that is inclined relative to the axis ( 31 ). The incoming air jets ( 53 ) therefore diverge and as a result create a central underpressure zone ( 57 ) about the axis ( 31 ) between the incoming air jets ( 53 ). By means of the central underpressure zone and the inclination of the incoming air jets, a rotation of the incoming air is achieved. In operation of the burner, hot gases from outside are aspirated into the peripheral underpressure zones ( 55 ) and, counter to the flow direction of the incoming air, into the central underpressure zone ( 57 ) between the incoming air jets ( 53 ). These flow conditions create ideal conditions for the combustion of gaseous, liquid and/or particulate fuel in a calm, cool, low-polluting flame. This combustion is practically independent of the size and shape of the combustion chamber and of the pressure conditions in the combustion chamber, for combustion installations of 16 kW to 1000 kW, or more.

1 . A method for combusting a liquid, gaseous, and/or particulate fuel at a low flame temperature and low pollutant emissions values, in which method fuel and incoming air are delivered to a combustion chamber and are ignited in the combustion chamber, 
 wherein    the incoming air is blown into the combustion chamber in two or more divergent incoming air jets spaced apart from one another;    by blowing in of incoming air, peripheral underpressure zones are created in the combustion chamber between each two incoming air jets, and oxygen-poor exhaust gases present in the combustion chamber are aspirated from outside, as a consequence of an underpressure in the peripheral underpressure zones, into the peripheral underpressure zones between each two incoming air jets;    and in which method, by the divergent blowing in of the incoming air jets centrally between the two or more incoming air jets, a central underpressure zone is created, and oxygen-poor exhaust gases present in the combustion chamber are aspirated axially and counter to a flow direction of the incoming air into the central underpressure zone.    
   
   
       2 . The method according to  claim 1 , wherein a flow axis of each incoming air jet is inclined relative to a center axis common to the incoming air jets and has a minimal spacing from the center axis that is greater than zero, and the flow axes of the incoming air jets intersect one another in the chamber.  
   
   
       3 . The method according to  claim 1  wherein liquid fuel is injected axially with a nozzle having a full-conical characteristic, mixed characteristic, or conical-jacket characteristic.  
   
   
       4 . The method according to  claim 3 , wherein the conical apex angle of the nozzle is at least 45°, advantageously over 60°, and at most 90°, and preferably is 80°.  
   
   
       5 . The method according to  claim 1  wherein gaseous fuel is admixed with the incoming air upstream of the blocking disk, advantageously upstream of a fan for the incoming air.  
   
   
       6 . The method according to  claim 1  wherein the incoming air is blown out at a dynamic overpressure of 4 to 50 millibars, advantageously between 7 and 28 mbar.  
   
   
       7 . A burner head for disposition on the end of an incoming air conduit of a low-NOx burner, 
 having a blocking disk closing off the incoming air conduit on the downstream end,    comprising:    a plurality of spaced-apart openings in the blocking disk, for splitting up a majority of the incoming air into incoming air jets, which openings are disposed in a ring;    guide blades at the openings for guiding each incoming air jet, flowing out of the incoming air conduit through an opening, in a divergent direction relative to the other incoming air jets;    and blocking blades, which are disposed between the openings, so as to reach peripheral underpressure zones between the incoming air jets.    
   
   
       8 . The burner head according to  claim 7 , wherein the guide blades at the openings are uniformly inclined and guide the outflowing incoming air jets in such a way that the flow axes of the incoming air jets intersect both one another and the center axis, common to the incoming air jets, in the chamber.  
   
   
       9 . The burner head according to  claim 7 , wherein the blocking blades and the guide blades are embodied integrally with the blocking disk.  
   
   
       10 . The burner head according to  claim 9 , wherein the blocking blades and the guide blades are shaped from a flat piece of sheet metal.  
   
   
       11 . The burner head according to  claim 7  wherein the blocking blades are embodied trapezoidally, and the guide blades are embodied adjoining one side of the trapezoid.  
   
   
       12 . The burner head according to  claim 11 , wherein the guide blades, along one edge, in particular a bending edge, adjoin the blocking blades, and at this edge the guide blades and blocking blades form an angle of between 95° and 160°, preferably between 110° and 140°.  
   
   
       13 . The burner head according to  claim 7  wherein the openings are embodied around a central body.  
   
   
       14 . The burner head according to  claim 13 , wherein the central body is a fuel nozzle for liquid fuel, and this fuel nozzle has a full-conical characteristic, mixed characteristic, or conical-jacket characteristic.  
   
   
       15 . The burner head according to  claim 13  wherein the guide blades accompany the central body in the flow direction of the incoming air.  
   
   
       16 . The burner head according to  claim 14 , wherein there is a fine annular gap around the fuel nozzle, so as to deliver only a small quantity of the incoming air to the fuel stream through the annular gap.  
   
   
       17 . The burner head according to  claim 7  wherein around the ring of openings, there are secondary air openings in the blocking disk, spaced apart from the openings.  
   
   
       18 . A blue-flame burner having an incoming air fan, an adjoining incoming air conduit, a fuel delivery means, an electric ignition, and a burner head as defined by  claim 7 .  
   
   
       19 . The blue-flame burner according to  claim 18 , comprising a gas delivery means and an oil nozzle.  
   
   
       20 . A boiler having a boiler chamber, a heat exchanger, and a burner as defined by  claim 18 .  
   
   
       21 . The boiler according to  claim 20 , wherein the boiler chamber is subdivided by a heat exchanger into a central combustion chamber and an exhaust gas chamber encasing the combustion chamber parallel to the inflow direction of the incoming air.  
   
   
       22 . The boiler according to  claim 21 , wherein the heat exchanger is a gap coil heat exchanger.  
   
   
       23 . An aperture plate for a burner head of a low-NOx burner and for use at the end of a burner pipe, comprising: 
 a plurality of spaced-apart openings for splitting up a majority of the incoming air into incoming air jets, which openings are disposed in a ring;    guide blades at the openings for guiding each incoming air jet, flowing out of the incoming air conduit through an opening, in a divergent direction relative to the other incoming air jets;    and blocking blades, which are disposed between the openings, so as to reach peripheral underpressure zones between the incoming air jets.