Pilot liquid fuel lance, pilot liquid fuel system and method of use

Abstract

A liquid fuel lance for a burner of a combustor of a gas turbine combustor, a liquid fuel system incorporating the liquid fuel lance and a method of operating the liquid fuel system. The liquid fuel lance has an elongate liquid fuel lance body and a liquid fuel tip. The elongate liquid fuel lance body includes a fuel flow passage and at least a first air passage and a second air passage. A liquid fuel tip defines a fuel outlet and arranged about the fuel outlet at least a first outlet and a second outlet to which air is independently supplied by the first air passage and the second air passage respectively, and wherein the amount of air supplied to the first air passage is variable.

1 . A liquid fuel lance for a burner of a combustor of a gas turbine combustor, the liquid fuel lance has a longitudinal axis and comprises:
 an elongate liquid fuel lance body and a liquid fuel tip,   wherein the elongate liquid fuel lance body comprises a fuel flow passage and at least a first air passage and a second air passage, the first air passage and the second air passage are arranged outwardly of the fuel flow passage,   wherein the liquid fuel tip defines a fuel outlet, and arranged about the fuel outlet is at least a first outlet and a second outlet to which air is independently supplied by the first air passage and the second air passage respectively, and wherein the amount of air supplied to at least the first air passage is variable.   
     
     
         2 . The liquid fuel lance as claimed in  claim 1 ,
 wherein the first air passage and the second air passage extend approximately parallel to the longitudinal axis.   
     
     
         3 . The liquid fuel lance as claimed in  claim 1 ,
 wherein the first air passage and the second air passage are helical about the longitudinal axis.   
     
     
         4 . The liquid fuel lance as claimed in  claim 3 ,
 wherein the first air passage and the second air passage are helical about the longitudinal axis by at least 180°.   
     
     
         5 . The liquid fuel lance as claimed in  claim 1 ,
 wherein the first air outlet extends about the axis at an angle in the range including 30° and 160°.   
     
     
         6 . The liquid fuel lance as claimed in  claim 1 ,
 wherein the first air outlet extends about the axis at an angle of 120°.   
     
     
         7 . The liquid fuel lance as claimed in  claim 1 ,
 wherein the at least a first outlet and the second outlet and the first air passage and the second air passage constitute a first air assist supply, and   a second air assist supply comprises at least first outlet and second outlet to which air is independently supplied by a first air passage and a second air passage respectively, and   wherein the amount of air supplied to the first air passage of the second air assist supply is variable.   
     
     
         8 . A liquid fuel system comprising:
 the liquid fuel lance as claimed in  claim 1 , and   an air supply control arrangement,   wherein the air supply control arrangement has a valve arrangement and a valve controller arranged to control the valve arrangement,   wherein the valve arrangement is arranged to operate at least the first air passage between a closed and an open position.   
     
     
         9 . The liquid fuel system as claimed in  claim 8 ,
 wherein the valve arrangement is arranged to operate at least the second air passage between a closed and an open position.   
     
     
         10 . The liquid fuel system as claimed in  claim 9 ,
 wherein the valve arrangement comprises at least a first valve arranged to vary air flow into the at least the first air passage and a second valve arranged to operate the second air passage,   wherein the first and second valves are in series with one another.   
     
     
         11 . The liquid fuel system as claimed in  claim 9 ,
 wherein the valve arrangement comprises at least a first valve arranged to vary air flow into the at least the first air passage and a second valve arranged to operate the second air passage,   wherein the first and second valves are in parallel with one another.   
     
     
         12 . A method of operating the liquid fuel system as claimed in  claim 8 , of the method comprising:
 supplying a total air flow to the at least first air passage and second air passage, and   adjusting the valve arrangement to supply the first air passage with 5% to 25% of the total air flow.   
     
     
         13 . The method of operating the liquid fuel system as claimed in  claim 12 , wherein the liquid fuel system comprises a plurality of liquid fuel injectors, the method further comprising:
 adjusting the valve arrangement to supply the first air passages with 5% to 25% of the total air flow to the plurality of liquid fuel injectors.   
     
     
         14 . The method of operating the liquid fuel system as claimed in  claim 12 , further comprising:
 adjusting the valve arrangement to supply the first air passage with 5% to 25% of the total air flow during engine start-up or weak extinction.   
     
     
         15 . The method of operating the liquid fuel system as claimed in  claim 12 , further comprising:
 adjusting the valve arrangement to supply the first air passage with approximately equal amounts of the total air flow during normal engine running.