Secondary fuel delivery system
View Patent ↗A secondary fuel delivery system for delivering a secondary stream of fuel and/or diluent to a secondary combustion zone located in the transition piece of a combustion engine, downstream of the engine primary combustion region is disclosed. The system includes a manifold formed integral to, and surrounding a portion of, the transition piece, a manifold inlet port, and a collection of injection nozzles. A flowsleeve augments fuel/diluent flow velocity and improves the system cooling effectiveness. Passive cooling elements, including effusion cooling holes located within the transition boundary and thermal-stress-dissipating gaps that resist thermal stress accumulation, provide supplemental heat dissipation in key areas. The system delivers a secondary fuel/diluent mixture to a secondary combustion zone located along the length of the transition piece, while reducing the impact of elevated vibration levels found within the transition piece and avoiding the heat dissipation difficulties often associated with traditional vibration reduction methods.
1. A secondary fuel delivery system comprising:
an elongated transition piece adapted to fluidly connect a primary combustion zone and a combustion engine turbine section, said transition piece being characterized by an elongated boundary wall surrounding a secondary combustion zone;
a substantially-ring-shaped manifold formed integral with said boundary wall, said manifold including an inlet port adapted to fluidly link a manifold interior with a source of secondary fluid;
a plurality of injector nozzles fluidly linking said manifold interior with said secondary combustion zone;
a flow acceleration region located within said manifold at a location where non-accelerated secondary fluid flow velocity is less than about 60% of the secondary fluid flow velocity exhibited proximate said inlet port;
a flowsleeve located within said flow acceleration region of said manifold, said flowsleeve adapted to increase fluid flow volume within said acceleration region to a level between about 65% to 120% of said secondary fluid flow velocity exhibited proximate said inlet port,
said flowsleeve representing a circumferentially-arcuate trough and including a blocking band constructed and arranged to divide said flow acceleration region of said manifold into a radially-inward portion and a radially-outward portion and having apertures through which said nozzles extend, said apertures fluidly connecting said manifold flow acceleration region radially-inward and radially-outward portions and being sized to allow said secondary fluid to flow radially outward from said radially-inward portion of said flow acceleration region, away from a manifold radially-inward boundary, along exteriors of said nozzles into said radially-outward of said flow acceleration region, and then change direction to enter and flow through the nozzles, before exiting the manifold and travelling into the secondary combustion zone;
said flowsleeve extending through a span having a circumferential span in the range of about 10 degrees to 120 degrees; and
wherein said blocking band, said apperatures, and said radially inward and outer portions of said manifold flow acceleration region are constructed and arranged to cooperatively increase flow velocity within said flow acceleration region to provide increased heat dissipation around said nozzles,
whereby said manifold exhibits increased stiffness and is resistant to vibration generated by said transition and wherein said flowsleeve compensates for secondary fluid cooling effectiveness losses at a region flow-wise-away from said inlet port.
2. The system of claim 1 , wherein said secondary fluid is fuel.
3. The system of claim 2 , wherein said secondary fluid further includes a diluent.
4. The system of claim 3 , wherein said diluent is steam.
5. The system of claim 3 , wherein diluent is an inert gas.
6. The system of claim 1 , further including effusion cooling holes located within said transition boundary wall, in a region proximate said manifold.
7. The system of claim 6 , wherein said cooling holes are generally disposed at an angle from about 5 to about 45 degrees with respect to the transition boundary wall.
8. The system of claim 1 , wherein said manifold includes a radially-outward cover, said cover including at least one circumferentially-extending gap adapted to release thermal stresses during operation.
9. The system of claim 8 , wherein at least one of said nozzles is threadably engaged with said manifold.
10. The system of claim 9 , wherein said manifold cover further includes at least one removable cap through which at least one of said nozzles may be accessed.