Flat Flame Burner Outlet Geometry for Thermal Load Reduction

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Solution Overview

Problem

Conventional flat-flame burners suffer from high thermal NOx pollution and excessive thermal load on the burner block, leading to reduced service life and energy inefficiencies due to the need for swirl internals and high combustion air pressures.

Innovation Solution

The flat-flame burner design places outlet openings closer to the end of the burner lance, reducing pollutant contamination and thermal load by allowing a majority of combustion gas to exit through outlets in the second sub-chamber, which is closer to the outlet opening than the transition to the first sub-chamber, thereby eliminating the need for additional swirl generation components and enhancing regenerative heat recovery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If conventional flat-flame burners use stationary or driven swirl internals to generate flame rotation, then the flame achieves rotational symmetry and lies flat against the burner quarl and furnace wall, but this generates pressure losses requiring higher combustion air pressures and energy losses

Engineering Contradiction:
Improveflame shapeVSAvoidenergy loss
Core Design Contradiction:
ShapeVSLoss of energy

Solution Approach 1:

The invention extracts and eliminates the swirl internals (both stationary and driven types) from the burner system entirely. Instead of using these separate components to generate flame rotation, the patent integrates swirl generation directly into the combustion air inlet geometry itself, allowing the inlet opening and supply to be arranged and oriented to generate tangential combustion air flow that produces the required flame rotation without additional energy losses

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical swirl internals (physical rotating or stationary components) with a geometric solution embedded in the combustion air supply system. The arrangement and orientation of the combustion air inlet opening and supply create the rotational flow through their spatial configuration alone, substituting mechanical swirl-generation mechanisms with a geometric flow-generation approach that avoids the associated pressure losses and energy consumption

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If conventional flat-flame burners use high combustion air pressures to overcome pressure losses from swirl internals, then sufficient air flow is maintained, but this generates additional energy losses

Engineering Contradiction:
Improvecombustion air flowVSAvoidenergy loss
Core Design Contradiction:
SpeedVSLoss of energy

Solution Approach 1:

The invention removes the source of pressure losses (swirl internals) from the system, allowing combustion air to flow at lower pressures while still achieving the required flow rates and flame characteristics. The tangential arrangement of the combustion air inlet opening and supply generates rotation without creating the pressure drops associated with conventional swirl-generating components

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The combustion air supply system serves dual functions: it provides the necessary combustion air flow and simultaneously generates the required flame rotation through its own geometric arrangement and orientation. This self-service approach eliminates the need for separate swirl-generating components and reduces the energy required to maintain adequate air flow

Inventive Principle:
Principle #25Self-service

3Stability of the object's composition

If outlet openings are positioned farther from the chamber outlet, then combustion gas has more time to mix and react, but this increases thermal load on the burner block and extends exposure time leading to higher thermal NOx formation

Engineering Contradiction:
Improvemixture stabilityVSAvoidthermal NOx pollution
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The invention positions outlet openings on the burner lance in the second sub-chamber at a location closer to the chamber outlet opening, changing the spatial dimension of gas exit. This dimensional repositioning allows combustion gas to exit the chamber sooner, reducing the time for thermal NOx formation while still achieving adequate mixing through the chamber's curved geometry and tangential flow patterns

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention accelerates the exit of combustion gas from the chamber by positioning outlet openings closer to the chamber outlet. This causes the combustion reaction products to 'rush through' the chamber more quickly, minimizing the residence time at high temperatures and thereby reducing thermal NOx formation while maintaining mixture stability through the chamber's geometric design

Inventive Principle:
Principle #21Skipping (Rushing through)

4Shape

If conventional burners use driven twist internals to generate swirl, then flame rotation is achieved, but this requires additional energy for driving these components

Engineering Contradiction:
Improveflame rotationVSAvoidenergy for drive
Core Design Contradiction:
ShapeVSUse of energy by moving object

Solution Approach 1:

The invention extracts and eliminates driven twist internals from the burner system, removing the need for additional energy input to drive rotation-generating components. Instead, the combustion air inlet opening and supply are arranged and oriented to generate tangential flow that produces flame rotation passively, without requiring mechanical driving energy

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The combustion air supply system generates the required flame rotation through its own geometric arrangement and orientation, serving the dual purpose of providing combustion air and creating rotational flow. This self-service mechanism eliminates the need for separate driven components and the energy they would consume

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design reduces thermal NOx pollution, extends the service life of burner components, and improves energy efficiency by eliminating the need for swirl internals and enabling better furnace atmosphere regulation, while allowing for high combustion air preheating and regenerative heat recovery.

Implementation Method 1

the combustion air inlet opening and a combustion air supply adjacent to the combustion air inlet opening upstream are arranged and oriented in such a way that a flow of combustion air entering through the combustion air inlet opening is tangent to the curvature of the wall

Methodology Applied
Scientific EffectTangential flow: Vortex Ring

Implementation Method 2

the outlet openings are arranged on the burner lance in such a way that the flow directions of the combustion gas flowing out of the outlet openings have a flow direction which is at an angle of >0° to the central axis

Methodology Applied
Scientific EffectAngled flow: Jet

Implementation Method 3

The heat transfer to the useful material occurs mainly through solid-state radiation from the burner quarl and furnace wall and through gas radiation from the flame

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentEP2458279B1Flat flame burner
Publication Date: 2017.06.07 VDEH BETRIEBSFORSCHUNGSINSTITUT GMBH
  • EP2458279B1 patent drawingFigure 1
  • EP2458279B1 patent drawingFigure 2
  • EP2458279B1 patent drawingFigure 3

AI summary

The flat flame burner (1) has a chamber (2) extending along a central axis (A) with a combustion air inlet opening (3) and an outlet opening (12).The chamber has a partial chamber (13), where another outlet opening (8) is arranged at the burner lance in another partial chamber (14). The partial chamber is arranged towards the central axis closer to the outlet opening than at the transition to former partial chamber.