Combustion – Combustion products return structure – Recirculation about mixing or combustion chamber wall or baffle
Patent
1994-01-19
1994-12-06
Dority, Carroll B.
Combustion
Combustion products return structure
Recirculation about mixing or combustion chamber wall or baffle
431352, F23L 900
Patent
active
053705262
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a burner for generating hot gas having a burner pipe, comprising a support pipe followed by a flame pipe, a nozzle arranged in the support pipe, a fuel jet exiting from the nozzle, a shield separating a precombustion chamber and a combustion chamber from one another in the burner pipe, the shield having a central passage penetrated by the fuel jet, recirculation openings arranged in the flame pipe and allowing an outer recirculation of cooled flue gas and an element for suppressing the outer recirculation during a starting phase of the burner.
A suppression of the outer recirculation is necessary because during the starting procedure too much heat is withdrawn from the gasifying process of the fuel and the flame for heating the outer recirculation gases and so an interruption or extinguishing of the flame occurs.
Burners of this type are known from DE-PS 39 06 854. The disadvantage of these burners is to be seen in the fact that due to the heating up of the elements provided for the suppression of the outer recirculation during the starting phase, the functioning of these elements is impaired.
The object underlying the invention is therefore to improve a burner of the generic type such that a reliable suppression of the outer recirculation is possible during the starting phase.
This object is accomplished in accordance with the invention, in a burner of the type described at the outset, in that the element for suppressing the outer recirculation is arranged within the burner pipe and is controllable via a control means guided through an interior of the support pipe.
The advantage of the inventive solution is to be seen in the fact that with this solution the element for suppressing the outer recirculation is arranged within the burner pipe and, therefore, is already subjected to lower temperatures. In addition, due to the control means being guided through the support pipe these are exposed to the cooled combustion air flowing into the combustion chamber and are, therefore, likewise shielded from high temperatures so that, altogether, the problems known from the state of the art are avoided in the inventive solution.
The term suppression of the outer recirculation during the starting phase is to be understood as a suppression of the outer recirculation present in hot burners by more than 50%, preferably more than 70% and in particular cases more than 85%. A complete suppression of the outer recirculation represents an extreme case of the inventive teaching.
In a particularly advantageous variation of the inventive solution, the element for suppressing the outer recirculation is an element cutting off a flow of recirculation gas within the burner pipe in the form of a slide. The flow of recirculation gas in the burner pipe can be suppressed in a constructionally simple manner and also reliably with a slide-like element of this type.
In a solution which is, constructionally, particularly simple, the slide-like element is a slide having an annular casing and moving in axial direction. This is the simplest solution from a constructional point of view and, therefore, the most inexpensive to realize.
In this respect, it is particularly advantageous for the slide to have a sealing surface which is cylindrical relative to the axis. With this cylindrical sealing surface, the slide can be arranged in the burner pipe in a simple manner.
For constructional reasons it is also favorable for the slide to be guided on an inner side of the flame pipe so that no additional measures at all are required for the guidance of the slide.
The solution described in the above is one of the most simple solutions from a constructional point of view and therefore one of the most inexpensive. In a somewhat more complicated solution which is, however, functionally improved, the slide-like element has a sealing surface which is annular relative to the axis and located in a plane extending essentially at right angles to the axis. With this construction of the sealing surface, problems which occur in the case of a c
REFERENCES:
patent: 2532740 (1950-12-01), Speer
patent: 2882843 (1959-04-01), Powell
patent: 2918117 (1959-12-01), Griffin
patent: 3869246 (1975-03-01), Hammond
patent: 4604104 (1986-08-01), Adis et al.
Adis Erich
Bader Manfred
Buschulte Winfried
Deutsche Forschungsanstalt fuer Luft - und Raumfahrt e.V.
Dority Carroll B.
Lipsitz Barry R.
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