Fuel injection system for a turbine engine

Abstract

A fuel system for a turbine engine for improving efficiency in a fuel system where a major stage and secondary stage can be combined and held to a relatively constant fuel ratio while maintaining acceptable engine dynamics and NOx emissions is disclosed. The fuel system may be formed from a first premix injector assembly stage positioned upstream from a combustor basket, whereby the first premix injector assembly stage is a secondary injector system. The fuel system may be formed from a first primary injector assembly stage, which is a main injector system, positioned downstream from the first premix injector assembly stage. The first premix injector assembly stage and the first primary injector assembly stage may be coupled together such that the fuel system is capable of emitting fuel into a combustor of the turbine engine via the first premix injector assembly stage and the first primary injector assembly stage simultaneously.

I claim: 
     
         1 . A fuel system for a turbine engine, comprising:
 a first premix injector assembly stage comprising at least one injector positioned upstream from a combustor basket, wherein the first premix injector assembly stage is a secondary injector system;   a first primary injector assembly stage comprising at least one injector positioned downstream from the first premix injector assembly stage, wherein the first primary injector assembly stage is a main injector system;   wherein the first premix injector assembly stage and the first primary injector assembly stage are coupled together such that the fuel system is capable of emitting fuel into a combustor of the turbine engine via the first premix injector assembly stage and the first primary injector assembly stage simultaneously; and   wherein a distance between the first premix injector assembly stage and a flame in the combustor is greater than a distance between the first primary injector assembly stage and the flame in the combustor.   
     
     
         2 . The fuel system of  claim 1 , wherein the first premix injector assembly stage and the first primary injector assembly stage are coupled together via a fuel manifold such that fuel supplied to the fuel manifold is distributed to the first premix injector assembly stage and the first primary injector assembly stage. 
     
     
         3 . The fuel system of  claim 2 , further comprising a tuning orifice plate positioned inline with the first premix injector assembly stage to regulate a fuel ratio of the combined first premix injector assembly stage and the first primary injector assembly stage. 
     
     
         4 . The fuel system of  claim 1 , wherein the first premix injector assembly stage is positioned upstream from a preswirler positioned within the fuel system. 
     
     
         5 . The fuel system of  claim 4 , wherein the first primary injector assembly stage is positioned at the preswirler. 
     
     
         6 . The fuel system of  claim 4 , wherein the first primary injector assembly stage is positioned downstream from the preswirler. 
     
     
         7 . The fuel system of  claim 1 , wherein the first premix injector assembly stage is configured to inject between about 10 percent and about 20 percent of the total fuel injected into the combustor. 
     
     
         8 . The fuel system of  claim 1 , wherein the first primary injector assembly stage is configured to inject between about 25 percent and about 45 percent of the total fuel injected into the combustor. 
     
     
         9 . The fuel system of  claim 1 , further comprising a pilot stage formed from at least one injector positioned downstream from the first premix injector assembly stage. 
     
     
         10 . The fuel system of  claim 9 , wherein the pilot stage is configured to inject less than 10 percent of the total fuel injected into the combustor. 
     
     
         11 . The fuel system of  claim 1 , further comprising a second primary injector assembly stage comprising at least one injector positioned downstream from the first premix injector assembly stage, wherein the second primary injector assembly stage is a main injector system. 
     
     
         12 . The fuel system of  claim 11 , wherein the first primary injector assembly stage emits at least 40 percent of a total fuel injected by the main injectors of the fuel system. 
     
     
         13 . The fuel system of  claim 12 , wherein the first primary injector assembly stage emits at least 50 percent of a total fuel injected by the main injectors of the fuel system. 
     
     
         14 . A fuel system for a turbine engine, comprising:
 a first premix injector assembly stage comprising at least one injector positioned upstream from a combustor basket, wherein the first premix injector assembly stage is a secondary injector system;   a first primary injector assembly stage comprising at least one injector positioned downstream from the first premix injector assembly stage, wherein the first primary injector assembly stage is a main injector system;   a second primary injector assembly stage comprising at least one injector positioned downstream from the first premix injector assembly stage, wherein the second primary injector assembly stage is a main injector system;   a pilot stage formed from at least one injector positioned downstream from the first premix injector assembly stage;   wherein the first premix injector assembly stage and the first primary injector assembly stage are coupled together such that the fuel system is capable of emitting fuel into a combustor of the turbine engine via the first premix injector assembly stage and the first primary injector assembly stage simultaneously; and   wherein a distance between the first premix injector assembly stage and a flame in the combustor is greater than a distance between the first primary injector assembly stage and the flame in the combustor.   
     
     
         15 . The fuel system of  claim 14 , wherein the first premix injector assembly stage and the first primary injector assembly stage are coupled together via a fuel manifold such that fuel supplied to the fuel manifold is distributed to the first premix injector assembly stage and the first primary injector assembly stage and further comprising a tuning orifice plate positioned inline with the first premix injector assembly stage to regulate a fuel ratio of the combined first premix injector assembly stage and the first primary injector assembly stage. 
     
     
         16 . The fuel system of  claim 15 , wherein the first premix injector assembly stage is positioned upstream from a preswirler positioned within the fuel system. 
     
     
         17 . The fuel system of  claim 15 , wherein the first premix injector assembly stage is configured to inject between about 10 percent and about 20 percent of the total fuel injected into the combustor, wherein the first primary injector assembly stage is configured to inject between about 25 percent and about 45 percent of the total fuel injected into the combustor, and wherein the pilot stage is configured to inject less than 10 percent of the total fuel injected into the combustor. 
     
     
         18 . The fuel system of  claim 15 , wherein the first primary injector assembly stage emits at least 40 percent of a total fuel injected by the main injectors of the fuel system. 
     
     
         19 . A fuel system for a turbine engine, comprising:
 a first premix injector assembly stage comprising at least one injector positioned upstream from a combustor basket, wherein the first premix injector assembly stage is a secondary injector system;   a first primary injector assembly stage comprising at least one injector positioned downstream from the first premix injector assembly stage, wherein the first primary injector assembly stage is a main injector system;   a second primary injector assembly stage comprising at least one injector positioned downstream from the first premix injector assembly stage, wherein the second primary injector assembly stage is a main injector system;   a pilot stage formed from at least one injector positioned downstream from the first premix injector assembly stage;   wherein the first premix injector assembly stage and the first primary injector assembly stage are coupled together such that the fuel system is capable of emitting fuel into a combustor of the turbine engine via the first premix injector assembly stage and the first primary injector assembly stage simultaneously;   wherein a distance between the first premix injector assembly stage and a flame in the combustor is greater than a distance between the first primary injector assembly stage and the flame in the combustor;   wherein the first premix injector assembly stage and the first primary injector assembly stage are coupled together via a fuel manifold such that fuel supplied to the fuel manifold is distributed to the first premix injector assembly stage and the first primary injector assembly stage;   a tuning orifice plate positioned inline with the first premix injector assembly stage to regulate a fuel ratio of the combined first premix injector assembly stage and the first primary injector assembly stage; and   wherein the first premix injector assembly stage is positioned upstream from a preswirler positioned within the fuel system.   
     
     
         20 . The fuel system of  claim 19 , wherein the first premix injector assembly stage is configured to inject between about 10 percent and about 20 percent of the total fuel injected into the combustor, wherein the first primary injector assembly stage is configured to inject between about 25 percent and about 45 percent of the total fuel injected into the combustor, wherein the pilot stage is configured to inject less than 10 percent of the total fuel injected into the combustor; and wherein the first primary injector assembly stage emits at least 40 percent of a total fuel injected by the main injectors of the fuel system.