Method and device for the combustion of fuel

Abstract

A method and device for the combustion of fuel in a fuel chamber resulting in combustion which is particularly low in nitrogen, wherein fuel and combustion air are mixed before entering the combustion chamber avoiding self-ignition; a first part of the mixture is introduced into the combustion chamber such that it circulates inside the combustion chamber; other fuel is added to the circulatory flow of the first part of the mixture until it is heated up to ignition conditions; and at least one second part of the mixture is introduced into the combustion chamber in such a way that is mixed with hot combustion gas from the circulatory flow, heated up and combusted until it leaves the combustion chamber.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is the US National Stage of International Application No. PCT / EP2004 / 011490, filed Oct. 13, 2004 and claims the benefit thereof. The International Application claims the benefits of European application No. EP03023210.2 filed Oct. 13, 2003, both of the applications are incorporated by reference herein in their entirety.FIELD OF THE INVENTION [0002] The invention relates to a method and a device for the combustion of fuel in a combustion chamber. BACKGROUND OF THE INVENTION [0003] The conventional method for converting fuel energy into heat is the oxidation or combustion of liquid fuel or gaseous fuel using an oxidizing agent such as atmospheric oxygen, for example. In the heavily loaded combustion systems of today, the problem exists in general that these systems must be configured for very low emissions, in particular for low NOx emissions. The combustion systems are expected to allow stable and complete combustion acr...

AI Technical Summary

Benefits of technology

[0009] According to the invention, a first volume of fuel (e.g. a combustion gas 1) is premixed with combustion air (avoiding self-ignition) before entry into the combustion chamber. In the subsequent reaction of parts of this mixture, a comparatively low temperature level is present, this being lower than the average temperature level of comparable combustion reactions. The combustion of this part of the mixture therefore results in relatively limited NOx formation. According to the invention, the mixture of fuel and combustion air is introduced into the combustion chamber in such a way that a first part of the mixture circulates in a recirculation vortex and at least one second part of the mixture mixes with the hot exhaust gas or combustion gas which flows away from the vortex. As a result of the mixing with the hot exhaust gas, this part of the mixture is sufficiently heated and combusts until it reaches the combustion chamber exit. However, separate piloting in conventional form is avoided according to the invention, and it is likewise possible to dispense with aerodynamic stabilization measures using swirl generators.

[0010] As a result of adding the remaining fuel into the recirculation vortex in one stage or even in a plurality of stages (e.g. combustion gas 2) in accordance with the invention, a quantity of energy is provided such that heating of the entire air / fuel mixture to ignition conditions is guaranteed or until ignition conditions are present. According to the invention, the further fuel is added to the mixture in such a way that homogeneous mixing into the combustion gas occurs at a low temperature level. Temperature peaks within the combustion chamber are thus avoided according to the invention. The result is a particularly limited formation of NOx from this region of the reacting combustion gas flow.

[0011] In an advantageous development of the claimed method, the fuel and the combustion air are mixed before entry into the combustion chamber in such a way that the ratio of combustion air to fuel is higher than the average air / fuel ratio of the combustion in the combustion chamber. As a result of the high air / fuel ratio according to the invention, a comparatively low temperature level is guaranteed, thereby reducing the formation of NOx.

[0013] Furthermore, a central afflux body for the first and / or second part of the mixture of fuel and combustion air advantageously offers the possibility of integrating an entity for discharging liquid fuel into the combustion chamber. A centrally arranged mixture discharge entity is moreover cooled by the mixture of fuel and combustion air which flows through it, whereby the mixture is minimally heated. The heating results in a further homogenization of the temperature level within the claimed circulation flow.

[0016] In contrast with a radial introduction of the first part of the mixture of fuel and combustion air, the further fuel is advantageously introduced into the combustion chamber in an essentially axial manner. Such an addition of remaining fuel (combustion gas 2) into the recirculation vortex provides the quantity of energy that is required in order to ensure the desired heating up of the entire air / fuel mixture to ignition conditions. A further advantage of an axial introduction of the further fuel is that the supplied further fuel also contributes to a cooling of the combustion chamber end wall at the same time, whereby the further fuel is slightly preheated.

Problems solved by technology

The combustion of this part of the mixture therefore results in relatively limited NOx formation.

The result is a particularly limited formation of NOx from this region of the reacting combustion gas flow.

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