Burner

Abstract

An aerodynamically stabilized premix burner essentially comprises a swirl generator (100) for generating a rotating combustion air flow (141), and means for introducing at least one fuel (142) into said combustion air flow. Furthermore, the burner is equipped with means (112) for introducing an axial air flow into the center of the generated rotational flow (144). According to the invention, this axial flow can be controlled, thus enabling an influence on the position and intensity of a flame stabilizing recirculation zone (123).

Description

[0001] The invention describes a burner for a heat generator according to the preamble of claim 1.STATE OF THE ART[0002] From EP 0 321 809, EP 0 780 629, WO 9317279, and EP 0 945 677, premixing burners are known in which a combustion air flow is introduced tangentially into a burner interior by means of a swirl generator and is mixed with fuel. At the burner outlet, the resulting vortex flow bursts open at a jump in cross section, inducing a recirculation zone which serves to stabilize the flame in operation of the burner.[0003] The axial position of the recirculation zone which arises is of critical importance for the stabilization of the flame, and in its turn is substantially determined by the axial flow in the center of the burner. If this axial flow is too weak, the recirculation zone, and with it the flame, migrates into the burner interior. The danger then exists of a flashback of the flame and a gradual overheating of the burner. If on the other hand the axial flow is too st...

AI Technical Summary

Benefits of technology

[0008] The crucial point of the invention is thus to provide the burner with a variable geometry of the central injection. It is possible in this manner to match the axial impulse of the central flow to the operating conditions at any given time. This makes it possible to affect the position and intensity of the recirculation zone in a targeted manner. It is thereby possible in a particularly advantageous manner to reduce the amount of air introduced centrally at a low burner load, such that the recirculation zone forms very near to the burner mouth or even partially within the burner interior, so that a superior flame stability results. At high load and high flame temperatures, in contrast, a high stability is already intrinsically inherent in the flame. Here the centrally introduced amount of air can be increased such that the recirculation zone comes to be reliably situated a distance downstream of the burner mouth. Thermal overloading of the burner is thereby prevented.

[0013] A further operating method results with advantageous operation in the combustion chamber in gas turbines. Here the variable central geometry in combination with the operating concepts of gas turbines with premixers, which are familiar to the skilled person, furthermore serves to ensure operation which is low in pollutants and at the same time stable and free from pulsation. Finally, a variation of the conditions can be set for individual burners in a targeted manner, in order to prevent acoustic resonances in the combustion chamber by a detuning of individual burners.

Problems solved by technology

The danger then exists of a flashback of the flame and a gradual overheating of the burner.

If on the other hand the axial flow is too strong, the recirculation zone can detach from the burner outlet and become unstable.

The consequence can be strong, damaging, combustion pulsations or even an extinction of the flame.

Solutions known from the state of the art are not capable of setting an optimum axial position of the recirculation zone under all operating conditions.

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