Biomass Burner Deflection Bodies for Stable Ignition
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Solution Overview
Problem
Biomass fuels with larger particle sizes experience delayed ignition and unstable combustion due to slower volatile component release, leading to flame formation at a distance from the burner, which impairs combustion stability and makes it difficult to achieve low-NOx operation.
Innovation Solution
The burner design incorporates deflection bodies within the primary tube gap upstream of the flame stabilizers, deflecting larger fuel particles towards the flame stabilizers, reducing their velocity and promoting early ignition near the burner outlet, while smaller particles follow the carrier gas for efficient combustion, with adjustable deflection surfaces and shapes to optimize fuel flow and turbulence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If biomass particles are combusted with conventional burner design, then combustion can be achieved, but ignition is delayed and combustion stability deteriorates due to slower volatile component release from larger particles
Solution Approach 1:
The burner divides the combustion air supply into multiple concentric zones (primary air in core tube, secondary air in annular gap, tertiary air in outer annular gap), allowing differentiated air supply to match the combustion needs of particles of different sizes and positions, thereby improving combustion stability and reducing ignition delay
Solution Approach 2:
The burner provides locally optimized conditions for different particle sizes: larger particles receive enhanced heating in the flame core region with primary air, while smaller particles are combusted in the surrounding zones, ensuring each particle type achieves optimal ignition and combustion rates
2Reliability
If secondary air flow is twisted to create negative pressure and backflow of hot combustion gases, then coal grain heating and ignition is supported, but the complexity of flow control increases
Solution Approach 1:
The secondary air flow is designed with adjustable swirl control to dynamically regulate the negative pressure and backflow volume of hot combustion gases, allowing the burner to adapt to different biomass dust characteristics and maintain reliable ignition under varying operating conditions
3Productivity
If biomass particles are combusted with standard air supply, then combustion occurs, but nitrogen oxide formation increases due to insufficient control of combustion zones
Solution Approach 1:
The combustion process is segmented into distinct zones with controlled air supply: primary combustion zone with limited air (sub-stoichiometric) to minimize NOx formation, followed by secondary and tertiary zones that complete combustion, thereby maintaining efficiency while reducing harmful emissions
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 ensures early and stable ignition of both large and small fuel particles, reducing particle velocity and enhancing turbulence, thereby stabilizing the flame and achieving low-NOx operation by directing larger particles to ignite near the burner outlet, improving combustion efficiency and stability across various fuel types.
Implementation Method 1
a plurality of deflection bodies (15) are arranged within the primary tube gap (54) upstream of the flame stabilizers (13) in such a way that one deflection body (15) in each case crosses the axis of every fifth, preferably every fourth, more preferably every 3, even more preferably every second and most preferably of each free flow path
Implementation Method 2
At the exit of the primary tube (4) to the combustion chamber, flame stabilizers (13) are arranged radially inwards, which lead to a flow separation and turbulence of the coal particles
Implementation Method 3
which lead to a flow separation and turbulence of the coal particles. In this way, a flow directed into the combustion chamber with high turbulence and concentration of coal particles is formed
Implementation Method 4
Due to the twisting of the secondary air flow, centrifugal forces are imposed on the flow, which cause a negative pressure in the core of the vortex field. This causes a return flow of hot combustion gases to the root of the flame in the core of the flame
Implementation Method 5
The high turbulence of the particle-rich fuel stream rapidly drives the volatile components out of the carbon particles
Implementation Method 6
a mixture of carbon particles and primary combustion medium (primary air) is fed to the burner via the dust line
Data Source
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AI summary
Burner (16) for particulate fuel, particularly suitable for the combustion of biomass fuels, comprising: - a primary tube (4); - a core tube (5) arranged in the primary tube (4); - wherein the primary tube (4) and the core tube (5) form a primary tube gap and wherein the primary tube gap is configured for ejecting a fluid mixture of a particulate fuel and a lifting gas (9); - a first secondary tube (3) concentrically surrounding the primary tube (4); - optionally a second secondary tube concentrically surrounding the first secondary tube (3) and optionally one or more further secondary tubes concentrically surrounding the respective inner tube;- a plurality of flame stabilizers (13) projecting radially into the cross-section of the primary tube gap at the outlet opening of the primary tube gap, wherein the flame stabilizers (13) define free flow paths whose axes run parallel to the longitudinal direction of the primary tube (4) between each pair of adjacent flame stabilizers (13), wherein one or more deflectors (15) are arranged within the primary tube gap upstream of the flame stabilizers (13) such that the respective deflector (15) intersects the axis of a free flow path. The invention further relates to a combustion system comprising the burners according to the invention and a method applied to such a burner.