Power plants – Combustion products used as motive fluid – Combustion products generator
Reexamination Certificate
1999-08-09
2001-07-24
Casaregola, Louis J. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combustion products generator
C060S740000, C431S173000
Reexamination Certificate
active
06263676
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a burner for operating an internal combustion machine, a combustion chamber of a gas turbine group or firing installation, having at least two hollow, half truncated-cone shaped bodies which are assembled within one other in such a way that their longitudinal axes of symmetry extend so that they are mutually radially offset and which enclose at least two tangential air inlet slots for a combustion inlet airflow and also enclose a hollow conical space, and having a nozzle arrangement for injecting liquid, highly reactive fuel into the hollow conical space, which nozzle arrangement is located in the region of the narrowest internal diameter of the hollow conical space. In addition, the invention relates to a method of operating an internal combustion machine, a combustion chamber of a gas turbine group or firing installation.
2. Discussion of Background
A burner of the generic type mentioned above is known, for example, from EP 0 321 809 B1 and is employed with great success for firing gas turbine installations. This type of burner is considered as a successful initial type for burners which have been designed for firing with highly reactive, gaseous and liquid fuels with a high calorific value of approximately 35 to 50 MJ/kg. In these, the liquid fuel is introduced in the form of a conically forming fuel spray to within the combustion chamber by means of a nozzle arrangement centrally fitted to the hollow conical space. The conical fuel spray is enclosed by a rotating combustion airflow flowing tangentially into the hollow conical space and is stabilized by it. It is only in the vortex collapse region, i.e. in the region of the so-called reverse flow zone, that the optimum, homogeneous fuel concentration is achieved over the cross section, so that the ignition of the fuel mixture takes place in this region. Gaseous fuel is injected from two tubes, which are arranged along the air inlet slots of the burner, through rows of holes transverse to the entering airflow.
The internal and external shape of the burner specified by the double-cone structure can be regarded as the end product of a comprehensive optimization process in which the burner has been optimized from the viewpoint of burning liquid fuel of high calorific value.
Building on the basis of the successful burner form concept which is described in EP 0 321 809 B1, it is appropriate to seek solutions promising success in permitting the additional combustion of low and medium calorific value fuels.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a novel further development of a burner whose spatial configuration is specifically optimized for the combustion of gaseous and liquid fuel of high calorific value, in such a way that the combustion of medium and/or low calorific value fuels is possible without impairing the shape and configuration of the burner and without deterioration of the emission figures. The measures to be taken for this purpose should, as far as possible, be suitable for the retrofitting of existing burners and have a simple configuration. Modifications necessary on the burner itself should be kept as small as possible so that, using a single type of burner, low, medium and high calorific value fuels can be burned. Finally, a method for operating a burner is to be provided such that the combustion of low, medium and high calorific value fuels with constant or reduced emission figures is possible. In addition, it should be possible to burn fuels of high hydrogen content without difficulty.
In accordance with the invention, an injection appliance is arranged upstream of each of the air inlet slots in such a way that the fuel to be introduced into the combustion airflow is injected into the air inlet slots parallel to the flow direction of the combustion inlet airflow. The parallel fuel feed avoids any turbulence within the combustion inlet airflow so that no irritating vortex formation, which leads to local fuel concentrations and causes uncontrolled ignition events, occurs.
The jet arrangement is, in particular, configured in such a way that the outlet velocity of the fuel from the jet arrangement has approximately the same flow velocity as that of the combustion inlet airflow introduced into the air inlet slots. Due to the isokinetic mass flow inlet behavior, any dynamic pressure differences are also avoided, by which means disturbing vortex formations can likewise be excluded.
In the case of the burner system described, which has two air inlet slots, the nozzle arrangement in accordance with the invention has two injection appliances which are respectively positioned upstream of the air inlet slots. The two injection appliances are permanently connected together by means of a framework and can be firmly and removably fitted to the burner by means of corresponding connecting elements. Each of the respectively provided inlet appliances extends lengthwise over the complete length of the air inlet slots and each has within it a preferably straight fuel supply line which is connected to the nozzle outlet region via a restricted supply duct.
The restricted supply duct can be configured either as a plurality of individual holes which have a distributed arrangement along the fuel supply duct or as a continuous supply slot which extends over the complete length of the injection appliance. The nozzle outlet region is preferably configured as a continuous slot duct which extends over the complete length of the injection appliance and has a duct length/width ratio which leads to a directed fuel jet, extending almost parallel and having in addition, as already mentioned above, a flow velocity matched to the flow velocity of the combustion inlet air.
REFERENCES:
patent: 5085575 (1992-02-01), Keller et al.
patent: 5169302 (1992-12-01), Keller
patent: 5244380 (1993-09-01), Dobbeling et al.
patent: 5375995 (1994-12-01), Dobbeling et al.
patent: 4237187A1 (1994-05-01), None
patent: 0321809B1 (1991-05-01), None
patent: 0724114A2 (1996-07-01), None
patent: 1535610 (1968-08-01), None
Keller Jakob
Keller Vera
Asea Brown Boveri AG
Burns Doane Swecker & Mathis L.L.P.
Casaregola Louis J.
Keller Vera
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