Modular Burner Primary Air Aspiration
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Solution Overview
Problem
Current modular burners emit excessive nitrogen oxides due to a high contribution of secondary air, which increases flame temperature above the critical value for NOx formation, especially at lower power regimes, leading to harmful emissions.
Innovation Solution
The modular burner design reduces the operating ratio between emission surfaces and free spaces between mixing modules, making the primary air flow predominant by minimizing secondary air supply, with a ratio of emission surfaces to free spaces reduced to less than 0.2, and increasing the spacing between mixing modules to enhance primary air aspiration, maintaining a high lambda value of the air-fuel mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ratio of emission surfaces to free spaces is maintained at about 0.3, then secondary air contribution is consistent and complete combustion is achieved, but flame temperature exceeds critical value for NOx formation
Solution Approach 1:
The invention changes the geometric parameter of the burner by reducing the ratio of emission surfaces to free spaces from about 0.3 to less than 0.2. This parameter change reduces the contribution of secondary air to combustion, thereby lowering flame temperature below the critical value for NOx formation while maintaining complete combustion through optimized primary air mixing
2Productivity
If secondary air supply is increased to ensure complete combustion, then combustion efficiency is improved, but flame temperature rises above critical value for NOx formation
Solution Approach 1:
The invention changes the geometric parameter of the burner by reducing the ratio of emission surfaces to free spaces from about 0.3 to less than 0.2. This parameter change reduces the contribution of secondary air to combustion, thereby lowering flame temperature below the critical value for NOx formation while maintaining complete combustion through optimized primary air mixing
3Quantity of substance
If the spacing between mixing modules is increased to enhance primary air aspiration, then primary air flow is improved, but the ratio of emission surfaces to free spaces decreases
Solution Approach 1:
The invention optimizes the spacing between mixing modules to enhance primary air aspiration while maintaining an overall ratio of emission surfaces to free spaces of less than 0.2. This involves adjusting module spacing and individual module dimensions to achieve the desired balance between primary air intake and emission surface area
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 effectively keeps the flame temperature below NOx formation levels even at low power regimes, reducing nitrogen oxide emissions without requiring modifications to the boiler or burner structure, and allows for precise power adjustment by varying the fuel gas supply pressure.
Implementation Method 1
at a Venturi tube arranged substantially perpendicular to an inlet opening of the flow conduit. The flow of fuel gas injected at the inlet of the flow conduit produces the drawing through the Venturi tube of so-called primary air that is mixed with the fuel inside the flow conduit.
Implementation Method 2
The air-fuel mixture, which exits from the flow conduit through the outlet openings of the mixing module, feeds a flame which extends above the mixing module
Data Source
Figure 1~2
Figure 3~4
Figure 4a
AI summary
A modular burner, comprising a plurality of mixing modules (10), flanked to each other and parallel to a longitudinal plane (Y), each of which has a length (L) measured parallel to the longitudinal plane (Y), wherein the mixing modules are separated from each other by a mounting pitch (P), measured as the distance between the mean longitudinal planes of two adjacent modules (10). The ratio between the length of the mixing modules (10) and the mounting pitch (P) is about 12.3.