Annular premixed pilot in fuel nozzle

Abstract

A combustor for a gas turbine engine has a head end portion that carries at least one fuel/air nozzle. Each fuel/air nozzle includes a premixed pilot nozzle having premix conduits that are configured with concentric axes that direct the fuel/air mixture axially from the premixed pilot nozzle. The premixed pilot nozzle can include an annular channel disposed radially outwardly from the premix and including air jets that direct air radially outwardly from the premix conduits.

Description

FIELD OF THE INVENTION[0001]The present invention generally involves a gas turbine engine that combusts a hydrocarbon fuel mixed with air to generate a high temperature gas stream that drives turbine blades to rotate a shaft attached to the blades and more particularly to the engine's fuel nozzle having a pilot nozzle that premixes fuel and air while achieving lower nitrogen oxides.BACKGROUND OF THE INVENTION[0002]Gas turbine engines are widely used to generate power for numerous applications. A conventional gas turbine engine includes a compressor, a combustor, and a turbine. In a typical gas turbine engine, the compressor provides compressed air to the combustor. The air entering the combustor is mixed with fuel and combusted. Hot gases of combustion are exhausted from the combustor and flow into the blades of the turbine so as to rotate the shaft of the turbine connected to the blades. Some of that mechanical energy of the rotating shaft drives the compressor and / or other mechani...

AI Technical Summary

Benefits of technology

[0007]In theory, the closer one comes to having at every point in the combustion chamber, a stoichiometric relationship between the fuel and air that undergoes combustion at a given temperature of combustion, the closer one comes to minimizing the generation of nitrogen oxides as byproducts of the combustion. With a fuel nozzle configured as described below, it becomes possible to achieve a more uniform equivalence ratio across the plane of the center body tip of the outer nozzle and thus more closely approximate achieving in the combustion chamber of the gas turbine engine such theoretical conditions of the desired stoichiometric relationship between the fuel and air that undergoes combustion at a given temperature of combustion. Moreover, to overcome one of the drawbacks of a diffusion flame type of pilot, a premix pilot also can be used as a pilot to stabilize the pilot flame, even in low fuel to air ratio to prevent an increase in NOx.

Problems solved by technology

However, there is a trade-off in performance of the gas turbine engine.

For as the ratio of fuel to air that is combusted is lowered, there is an increased tendency of the flame of the fuel nozzle to blow out and thus render unstable the operation of the gas turbine engine.

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