Flame burner and method for flame burning a metallic surface

Abstract

The invention relates to a flame burner having a nozzle ( 10 ) disposed in a head, wherein in addition to annularly disposed gas supply channels ( 11 ) the nozzle has a central gas supply opening ( 12 ), which has a laval nozzle-like region and a stabilizing region having a consistent diameter connected thereto in the flow direction. In order to flame burn a metallic surface the oxygen gas guided through a central nozzle of a flame burner is incited to oscillate in such a manner, such that a pulsating oxygen flow exiting the nozzle mouth is formed at the speed of sound, or at supersonic speed.

1 . A flame burner having a nozzle disposed in a head, wherein in addition to annularly disposed gas-supply passages the nozzle has a central gas-supply duct wherein the central gas-supply duct has directly succeeding regions in the flow direction, namely
 a first region tapering in to a minimal inner diameter,   a second region whose inner surface flares to a larger diameter than the minimal diameter, and   a third region extending up to the nozzle outlet mouth and having a uniform cross-sectional profile, preferably a uniform cylindrical inner diameter.   
   
   
       2 . The flame burner according to  claim 1  wherein a length of the first region is smaller than a length of the second region. 
   
   
       3 . The flame burner according to  claims 1  wherein a diameter of the third region is smaller than a maximum initial diameter at an upstream end of the first region. 
   
   
       4 . The flame burner according to  claim 1  wherein diameters of the three regions and their lengths are adjusted to one another such that gas exits as pulses at the nozzle outlet mouth. 
   
   
       5 . The flame burner according to  claim 4  wherein the pulse frequency at the nozzle outlet mouth is 100 to 650 Hz. 
   
   
       6 . The flame burner according to  claims 4  wherein the maximum gas flow velocity is 2 Ma at predetermined values of the oxygen and the combustion gas pressure. 
   
   
       7 . The flame burner according to  claim 1  wherein the central gas-supply duct has an annular cross-section. 
   
   
       8 . The flame burner according to  claim 1  wherein the nozzle head is liquid-cooled, particularly water-cooled. 
   
   
       9 . A method for flame burning a metallic surface, the method comprising the steps of:
 feeding gaseous oxygen guided through a central nozzle of a flame burner; and   controlling flow of the gaseous oxygen in the burner such that the gaseous oxygen is made to oscillate such that and a pulsating oxygen flow exiting the nozzle outlet mouth is formed at the speed of sound or at supersonic speed.   
   
   
       10 . The method for flame burning according to  claim 9 , further comprising the step of
 subdividing the gaseous oxygen flow into a central flow and peripheral flows.   
   
   
       11 . The method according to  claims 9  further comprising the step of
 maintaining the ratio of the oxygen pressure upstream of the central nozzle to the ambient pressure is to between 1 and 200 such that the ratio of the oxygen pressure at the nozzle outlet surface to the ambient pressure is between 0.1 to 100.