Bell-Shaped Burner Flame Segmentation for Low NOx Combustion
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Solution Overview
Problem
Thermal post-combustion devices face challenges in achieving optimal combustion efficiency while minimizing the formation of nitrogen oxides (NOx) and carbon monoxide (CO) due to the trade-off between high combustion temperature and incomplete combustion issues in compact flame configurations.
Innovation Solution
A burner design featuring a combustion nozzle with an outer and inner tube, including a constriction at the flow path end, creates a compact 'bell-shaped' flame that is difficult for oxygen to access, reducing flame temperature and promoting complete combustion through turbulence, ensuring low-temperature oxidation of impurities with a V-shaped groove and adjustable outlet gap for varying capacities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a compact flame configuration is used, then combustion efficiency is improved, but flame temperature becomes too high causing excessive NOx formation
Solution Approach 1:
The flame is segmented into an inner core region and an outer region through the bell-shaped configuration. The inner tube creates a central low-velocity zone that confines the high-temperature core, while the outer turbulent region provides mixing and cooling, effectively dividing the flame into functional zones that simultaneously achieve complete combustion and limit peak temperatures
Solution Approach 2:
The bell-shaped flame configuration changes the velocity distribution parameters within the flame structure. The conically tapering inner tube creates a specific velocity profile with a low-velocity core region, transforming the flame from a uniform high-velocity structure to one with differentiated velocity zones, thereby reducing peak temperatures while maintaining combustion efficiency
2Productivity
If a compact flame configuration is used, then combustion efficiency is improved, but incomplete combustion occurs with high CO levels
Solution Approach 1:
The flame structure is segmented into an inner low-velocity core region for stable combustion and an outer high-velocity turbulent region for complete oxidation. This segmentation allows the inner region to maintain combustion stability while the outer region ensures complete burning of combustible components, preventing CO formation
Solution Approach 2:
The design creates an outer turbulent region that extends beyond the minimum required for combustion completion. This excessive mixing and turbulence in the outer flame region ensures that even under varying operating conditions, complete combustion is achieved, preventing CO formation while maintaining the compact overall flame structure
3Adaptability or versatility
If the outlet gap area is increased for higher capacity, then adaptability is improved, but device complexity increases
Solution Approach 1:
The nozzle incorporates movable components that allow dynamic adjustment of the outlet gap area. The inner tube can be positioned at different locations within the outer tube, and the adjustable baffle can change the effective flow area, enabling the system to adapt to different capacity requirements through simple positional changes rather than complex mechanical reconfigurations
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
The burner achieves improved combustion values by ensuring complete oxidation of impurities at low temperatures, reducing NOx and CO formation, and allowing for adaptability to different exhaust gas capacities through adjustable nozzle settings.
Implementation Method 1
the turbulence device, which, despite the compact flame, ensures complete combustion of the impurities and fuel gas carried in the exhaust gas by generating flow vortices between the exhaust air stream and the gas ring
Implementation Method 2
complete oxidation of the combustible components is achieved at the low temperature of the combustion chamber
Implementation Method 3
complete oxidation of the combustible components is achieved
Data Source
Figure 1
Figure 2~3
AI summary
The invention describes a burner for a thermal post-combustion device, which has a burner jet arranged in a housing. Arranged on the end region of the housing is a swirl apparatus, through which the exhaust gas to be purified can be made to flow. The burner jet comprises an outer tube and an inner tube, wherein it is possible for combustion gas to be made to flow through the interspace between said two tubes as far as an annular outlet gap in the end region thereof. The flow path for the combustion gas has a bottleneck in the vicinity of the outlet gap. In this way, a compact flame can be achieved, the form of which can be designated “bell-shaped” and which, for a given volume, has a relatively small surface. Although, such a flame has poor CO2 values, the swirl apparatus ensures that the exhaust gas burns in the flame with very low NOx and CO values.