US 9,810,432 B2
Method for premixing air with a gaseous fuel and burner arrangement for conducting said method
Fernando Biagioli, Fislisbach (CH); and Madhavan Narasimhan Poyyapakkam, Rotkreuz (CH)
Assigned to ANSALDO ENERGIA SWITZERLAND AG, Baden (CH)
Filed by ALSTOM Technology Ltd, Baden (CH)
Filed on Apr. 14, 2015, as Appl. No. 14/685,945.
Claims priority of application No. 14165191 (EP), filed on Apr. 17, 2014.
Prior Publication US 2015/0300646 A1, Oct. 22, 2015
Int. Cl. F23R 3/14 (2006.01); F23R 3/28 (2006.01); F23C 7/00 (2006.01)
CPC F23R 3/14 (2013.01) [F23C 7/004 (2013.01); F23R 3/286 (2013.01); F23C 2900/07001 (2013.01); F23D 2900/14021 (2013.01); F23D 2900/14701 (2013.01)] 29 Claims
OG exemplary drawing
 
1. A method for premixing air with a gaseous fuel for being burned in a combustion chamber, said method comprising:
guiding said air in an air stream along a burner axis through a coaxial air tube into a combustion chamber arranged at an end of said air tube;
impressing a swirl on said air stream by passing it through a first swirl device concentrically arranged within said air tube and comprising a plurality of radially oriented first blades;
injecting gaseous fuel into said air stream at said first swirl device; and
mixing said air in said air stream with the injected gaseous fuel in a first mixing zone arranged just after said first swirl device;
sending the mixed fuel/air stream leaving said first mixing zone through a second swirl device concentrically arranged within said air tube and
comprising a plurality of radially oriented second blades to reduce the swirl of the mixed fuel/air stream;
wherein the camber line of a blade of the second blades is aligned at a leading edge of the blade of the second blades with the camber line of a blade of the first blades at a trailing edge of the blade of the first blades to avoid flow separation,
injecting gaseous fuel into said mixed fuel/air stream at said second swirl device; and
further mixing said mixed fuel/air stream with the injected gaseous fuel in a second mixing zone arranged just between said second swirl device and said combustion chamber.