Burner for Particulate Fuel

Abstract

Disclosed is a burner for particulate fuel, in particular made of biomass, with a primary tube and a core tube arranged in the primary tube. The primary tube and the core tube form a primary tube gap and the primary tube gap is configured to guide a flow of particulate fuel and gaseous combustion means from an inlet-side end to an outlet-side opening of the primary tube. In order to prevent the drawbacks occurring when using coarse-grain particles, preferably biomass, as a fuel for dust firing, or at least to reduce them without having to accept an increased outlay for equipment and/or additional energy losses, at least one device is provided for centring the flow within the primary tube in the region of the outlet-side end of the primary tube.

Description

BACKGROUND OF THE INVENTION[0001]1) Field of the Invention[0002]The invention relates to a burner for particulate fuel, in particular made of biomass, with a primary tube and a core tube arranged in the primary tube, the primary tube and the core tube forming a primary tube gap and the primary tube gap being configured to guide a flow of particulate fuel and gaseous combustion means from an inlet-side end to an outlet-side opening of the primary tube.[0003]2) Description of Prior Art[0004]Burners for the combustion of particulate fuels, such as, in particular, coal, in a combustion chamber have been known for some time. Dust firing is also referred to in this connection.[0005]A burner of this type is described, for example, in EP 0 571 704 A2. The burner has a core tube, which has air flowing through it, and has a burner gun for igniting the particulate fuel. Arranged concentrically with respect to the core tube is a primary tube, which, with the core tube, forms an annular gap, whi...

AI Technical Summary

Benefits of technology

[0025]The at least one flow director may be oriented in the longitudinal direction of the primary tube. The swirl of at least one part of the primary air flow close to the core tube is at least weakened thereby, which can have a favourable effect on the flow conditions. In order to direct the flow but not to lastingly disrupt it, the at least one flow director should be much wider in the longitudinal direction than in the peripheral direction of the primary tube gap.

[0026]The at least one flow director may, as an alternative thereto, also be oriented transverse to the longitudinal direction, i.e. partially in the peripheral direction, of the primary tube. In this case, the orientation of the at least one flow director may differ from an orientation in the longitudinal direction of the primary tube in such a way that the swirl of the primary air flow is intensified by the at least one flow director, at least for a part of the primary air flow close to the core tube. The at least one flow director may, however, also reduce the swirl of the primary air flow in an also possible orientation pointing more in the longitudinal direction of the primary tube. The at least one flow director may, however, also be oriented in the opposite direction to the swirl direction of the primary air flow. This may, for example, lead to the fact that the swirl direction of the primary air flow is reversed at least for a part of the primary air flow close to the core tube. In order to intensify the swirl of the primary air flow in regions, it may be expedient to incline the at least one flow director by 35° to 45° relative to the longitudinal direction of the primary tube. In order to weaken the swirl of the primary air flow in regions, it may be favourable to incline the at least one flow director by less than 25°, in particular less than 15°, relative to the longitudinal direction of the primary tube.

[0027]Depending on the boundary conditions in terms of flow technology, each of these orientations of the at least one flow director may entail positive effects. Basically, by means of a swirl, which has a different strength or is differently directed, of parts of the primary air flow, a separation in terms of flow technology of these parts can be achieved, as the latter have different properties in terms of flow technology. To enable a control of the burner, the at least one flow director may be variable with regard to its orientation, i.e. incline compared to the core tube.

Problems solved by technology

Thus, a flow is produced, which is directed into the combustion chamber, with a high degree of turbulence and coal particle concentration.

For this purpose, the biomass has to be very finely ground, however, which, because of the usually fibrous and tough structure of conventional biomasses, is linked with an increased outlay for equipment and energy.

In particular, the fine grinding of biomass often entails a high degree of wear of the equipment used for this.

The volatile components of the biomass particles are already expelled more slowly because of their size, which can impair stable combustion of the biomass.

The larger carrying air quantity flowing through the annular gap between the primary tube and the core tube can, together with a delayed release of volatile components, lead to a local air excess during the combustion.

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