Fuel Staging in a Burner

Abstract

A method for a staging operation at start up of a burner for a gas turbine engine combustor is provided. The method will stabilize the combustion of a lean-rich partially premised low emission burner for a gas turbine combustor at all engine load conditions. The method includes, adding fuel mixed with air to the pilot combustor, igniting the mixture utilizing an igniter provided at an upstream end of the pilot combustor for initiating a lean flame inside the pilot combustor and for providing the flow of the radicals and heat, imparting a swirl of fuel and air at the outside at the exit of the pilot combustor at the upstream end of the combustion room for creating and sustaining the main lean flame and gradually adding a swirl of air and fuel for establishing a full load stage to at least one channel.

1 .- 3 . (canceled) 
     
     
         4 . A method for staging an operation at start up of a burner for a gas turbine engine combustor, comprising:
 providing a burner housing, the burner housing enclosing the burner and a pilot combustor;   adding fuel mixed with air to the pilot combustor;   igniting the mixture utilizing an igniter provided at an upstream end of the pilot combustor for initiating a lean flame inside the pilot combustor and for providing a flow of an unquenched concentration of radicals at non-equilibrium and heat to a downstream main combustion room;   imparting a first swirl of fuel and air outside a first exit of the pilot combustor at an upstream end of an combustion room for creating and sustaining a main lean flame in the main combustion room;   generating a second swirl of air and fuel from a second exit of a first lean premixing channel downstream of the first exit and from a third exit of a second lean premixing channel downstream of the second exit,   wherein the burner includes axially opposed upstream and downstream end portions, and   wherein the pilot combustor is located at an upstream end of the burner,   wherein the pilot combustor is provided with fuel and air for burning fuel for a creation of the flow of radicals and heat from a pilot combustion zone directed downstream along a center line of the pilot combustor through a throat at an exit of the pilot combustor, and   wherein the burner is further provided with the main combustion room defined by a plurality of quarl walls downstream of the exit of the pilot combustor for housing the main flame and a main recirculation zone for recirculating unburnt radicals.   
     
     
         5 . The method as claimed in  claim 4 , further including:
 adjusting, after ignition, an equivalence ratio of a pilot combustor flame in the pilot combustor to be a lean flame below equivalence ratio 1.   
     
     
         6 . The method as claimed in  claim 5 , wherein the equivalence ratio is 0.8. 
     
     
         7 . The method as claimed in  claim 4 , further including:
 adjusting, after ignition, an equivalence ratio of a pilot combustor flame in the pilot combustor to be a rich flame above equivalence ratio 1.   
     
     
         8 . The method as claimed in  claim 7 , wherein the equivalence ratio is between 1.4 and 1.6. 
     
     
         9 . The method as claimed in  claim 5 , further including:
 providing cooling air for cooling a plurality of walls of the pilot combustor;   preheating through the cooling of the plurality of walls the cooling air to a temperature above 750° C.; and   adding fuel to the cooling air to an amount that corresponds to equivalence ratios up to more than 3.   
     
     
         10 . The method as claimed in  claim 7 , further including:
 providing cooling air for cooling a plurality of walls of the pilot combustor;   preheating through the cooling of the plurality of walls the cooling air to a temperature above 750° C.; and   adding fuel to the cooling air to an amount that corresponds to equivalence ratios up to more than 3.   
     
     
         11 . The method as claimed in  claim 6 , further including:
 providing cooling air for cooling a plurality of walls of the pilot combustor;   preheating through the cooling of the plurality of walls the cooling air to a temperature above 750° C.; and   adding fuel to the cooling air to an amount that corresponds to equivalence ratios up to more than 3.   
     
     
         12 . The method as claimed in  claim 8 , further including:
 providing cooling air for cooling a plurality of walls of the pilot combustor;   preheating through the cooling of the plurality of walls the cooling air to a temperature above 750° C.; and   adding fuel to the cooling air to an amount that corresponds to equivalence ratios up to more than 3.