Burner with adjustable radial fuel profile

Abstract

A burner ( 1 ) with a longitudinal burner axis ( 2 ) and a mixing channel ( 3, 4 ), formed in an annular manner around the longitudinal burner axis ( 2 ), for the mixing of fuel and air. Each mixing channel is bounded radially on the inside by a channel hub ( 5, 6 ) and radially on the outside by a channel outer wall ( 7, 8 ). A fuel concentration distribution in the mixing channel ( 3, 4 ) from the channel hub ( 5, 6 ) to the channel outer wall ( 7, 8 ) being adjustable by adjusting the introduction of fuel to provide an adjustable fuel concentration distribution at respective radial locations across each mixing claimed. Also a combustion system ( 20 ) with a burner ( 1 ) and to a method for operating a burner ( 1 ).

What is claimed is: 
     
         1 . A burner having a longitudinal burner axis;
 a first mixing channel extending annularly around the longitudinal burner axis, and the first mixing channel being configured and operable for mixing of fuel and air in the burner;   a channel hub bounding the first mixing channel radially on an inward side thereof, and a channel outer wall bounding the first mixing channel radially on an outward side thereof; and   a device in the first mixing channel configured for providing an adjustable fuel concentration distribution in the first mixing channel radially from the channel hub to the channel outer wall.   
     
     
         2 . The burner as claimed in  claim 1 , further comprising a burner stage comprising a first and a second distribution system for the mixing channel;
 respective first fuel jets of the first distributing system being arranged at at least one of substantially radially inward and substantially radially outward in the first mixing channel; and   respective second fuel jets of the second distributing system being arranged substantially radially in a middle region in the first mixing channel between radially inward and radially outward sides of the first mixing channel.   
     
     
         3 . The burner as claimed in  claim 2 , further comprising a second, annular mixing channel which is surrounded by the first mixing channel;
 a third distributing system in the second annular mixing channel, the third distributing system having third fuel jets and the third fuel jets are arranged substantially in a radially middle region to a radially outward region in the second annular mixing channel; and   a fourth distributing system having fourth fuel jets and the fourth fuel jets are arranged substantially in the radial middle region of the second annular mixing channel to a radially inward region in the second annular mixing channel.   
     
     
         4 . The burner as claimed in  claim 3 , further comprising blades in each of the mixing channels, the blades having inner fuel passages of the blades and the inner fuel passages located in the respective mixing channel in which the blades are located, and the fuel passages are configured and operable for injection of fuel by at least one of the distributing systems for the respective mixing channel. 
     
     
         5 . The burner as claimed in  claim 4 , further comprising a plurality of the blades in each of the mixing channels, wherein successive blades of the plurality of the blades in each mixing channel are neighboring one another, and different ones of the respective distributing systems of each mixing channel are assigned to neighboring blades in the mixing channels. 
     
     
         6 . The burner of  claim 4 , wherein each of the blades is respectively assigned to and configured to receive fuel from at least two of the distributing systems. 
     
     
         7 . A combustion system including a burner as claimed in  claim 2 ;
 the combustion system further comprising a combustion chamber having a first end, a burner arranged in the first end of the combustion chamber; and   a device configured for measuring alternating pressure amplitudes or accelerations in individual frequency bands in at least one of the combustion chamber and the burner.   
     
     
         8 . A method for operating a burner in which fuel is injected into a mixing channel for mixing of fuel and air, the method comprising:
 injecting fuel of one burner stage via at least two distributing systems, each distributing system having a different fuel profile over a cross-section of the mixing channel; and   selectively influencing operation-restricting or operating-enhancing oscillation modes in corresponding load ranges in fuel distribution to the distributing systems for changing the fuel distribution over the cross-section of the mixing channel.   
     
     
         9 . The method as claimed in  claim 8 , further comprising:
 continuously measuring alternating pressure amplitudes or accelerations in individual frequency bands in a combustion chamber or at the burner;   upon an increase in an amplitude of a mode above a fixed limit value, changing the fuel of one of the distributing systems as a proportion of the total amount of the fuel being injected by the two distributing systems for adjusting for the increase in the amplitude of the mode.   
     
     
         10 . The method of  claim 8 , wherein the mixing channel is an annular channel and the method further comprising changing the fuel distribution in the mixing channel such that a selected radial fuel profile is altered. 
     
     
         11 . The method as claimed in  claim 10 , further comprising changing the fuel distribution such that a proportion of fuel in a radial middle region of the annular mixing channel is changed with respect to a radially inner and a radially outer region of the annular mixing channel. 
     
     
         12 . The method as claimed in  claim 10 , further comprising changing the fuel distribution such that a proportion of fuel in a radially inner region of the annular mixing channel is changed with respect to a proportion of fuel in a radially outer region of the annular mixing channel. 
     
     
         13 . The method as claimed in  claim 11 , further comprising:
 changing fuel distribution in an annular main channel such that a proportional distribution of fuel in a radial middle region in the main channel is changed with respect to a proportional distribution of fuel to a radially inner and a radially outer regions of the main channel; and   changing fuel distribution in an annular pilot channel that is surrounded by the main channel so that a proportion of fuel in a radially inner region of the pilot channel is changed with respect to a proportion of fuel in a radially outer region of the pilot channel.   
     
     
         14 . A method for operating a burner according to  claim 1 , in which fuel is injected into a mixing channel for mixing of fuel and air, the method comprising:
 injecting fuel of one burner stage via at least two distributing systems, each distributing system having a different fuel profile over a cross-section of the mixing channel; and   selectively influencing operation-restricting or operating-enhancing oscillation modes in corresponding load ranges in fuel distribution to the distributing systems for changing the fuel distribution over the cross-section of the mixing channel.