Device for stabilizing combustion in gas turbine engines

Abstract

Disclose is a burner for a gas turbine combustor that uses a central bluff body flame holder and a quarl to shape the recirculation zone in order to stabilize the combustion process. The burner includes, among other elements, a cylindrical main body and a flame holder. The flame holder is disposed within a fuel-air mixing chamber and includes a base portion and an elongated bluff body. The base portion engages with the main body of the burner in a supporting manner and the elongated bluff body extends in an axially downstream direction from the base portion through the internal mixing chamber so as to position a combustion ignition point downstream of the internal mixing chamber. In a representative embodiment, the burner further includes a quarl device disposed adjacent to the downstream end portion of the burner main body. The quarl device defines an interior recirculation chamber and a burner exit. The interior recirculation chamber is adapted for receiving precombustion gases from the mixing chamber and for recirculating a portion of the combustion product gases in an upstream direction so as to aid in stabilizing combustion.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application No. 60 / 500,517 filed Sep. 5, 2003, which is herein incorporated by reference in its entirety.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The subject invention relates to burners for gas turbines, and more particularly, to burners adapted to stabilize engine combustion, and still further, to burners which use a quarl device in combination with and a central bluff body flame holder to stabilize the combustion process. [0004] 2. Background of the Related Art [0005] Gas turbines are employed in a variety of applications including electric power generation, military and commercial aviation, pipeline transmission and marine transportation. In a gas turbine engine, fuel and air are provided to a burner chamber where they are mixed and ignited by a flame, thereby initiating combustion. Several major technical problems are associated with the combusti...

AI Technical Summary

Benefits of technology

[0022] The burner further includes a quarl device disposed adjacent to the downstream end portion of the main body. The quarl device defines an interior recirculation chamber and a burner exit. The interior recirculation chamber is adapted for receiving precombustion gases from the mixing chamber and for recirculating a portion of the combustion products gases in an upstream direction so as to aid in stabilizing combustion.

Problems solved by technology

Several major technical problems are associated with the combustion process in gas turbine engines.

These problems include, for example, thermal efficiency of the burner / combustor, proper mixing of the fuel and air, flame stabilization, the elimination of pulsations and noise, and the control of polluting emissions, especially nitrogen oxides (NOx).

As a result, the flux of the hot and chemically reactive combustion products that are transported upstream is low and the combustion is less stable, especially when the combustion is lean.

However, in burners which use a quarl, when the swirl strength is strong, the flame has a tendency to move upstream, deep inside the burner causing damage to the burner components.

In addition to damaging the burner hardware, the uncontrolled movement of flame deep into the burner can result in high NOx emissions.

Moreover, stability issues can become magnified when changes are made to the fuel / air ratio.

The continually varying flame speed often results in a shifting flame position, causing combustion pressure oscillations and noise.

Combustions instability can also occur when the flame moves inside the burner causing the fuel / air ratio to become richer, which causes the flame to move deeper into the burner.

However, this will result in a cyclic process of the flame moving in and out of the burner.

This common instability problem can result in very high-pressure pulsations and an increase in NOx emissions.

The amplitude of the pressure pulsations can exceed 0.1 bar and are destructive to the gas turbine engine.

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