Coal Nozzle Flow Constriction for NOx Reduction
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Solution Overview
Problem
Current pulverized coal burning technologies face challenges in minimizing the production of nitrogen oxides (NOx) during combustion, leading to air pollution.
Innovation Solution
A pulverized solid fuel nozzle design featuring a flow section with a globally minimal cross-sectional area that increases continuously from a constriction, incorporating expansion sections and optional catalyst coatings, igniters, and cooling means to maintain a flame front within the nozzle, facilitating fuel-rich combustion and reducing NOx formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional burner designs are used, then combustion efficiency is maintained, but NOx emissions increase due to high temperature combustion
Solution Approach 1:
The patent changes the physical parameters of the combustion process by introducing a flow constriction that creates a fuel-rich zone with lower oxygen concentration. This parameter change allows combustion to occur at lower temperatures, reducing NOx formation while maintaining efficiency through the controlled fuel-rich environment that promotes complete combustion
Solution Approach 2:
The patent applies local quality by creating a specific zone within the nozzle (the flow constriction area) that has different combustion characteristics from the rest of the system. This localized fuel-rich zone with controlled oxygen availability enables low-temperature combustion that reduces NOx emissions while the overall system maintains high combustion efficiency
2Object-affected harmful factors
If flame front is held outside the flow section, then NOx is reduced, but combustion efficiency decreases
Solution Approach 1:
The patent uses the flow constriction as an intermediary element that mediates between the fuel supply and the combustion zone. This constriction creates a transition zone that allows the flame front to be positioned optimally - effectively outside the main flow section for NOx reduction while maintaining close coupling for combustion efficiency through the controlled flow dynamics
3Ease of manufacture
If the flow section has uniform cross-section, then manufacturing is simple, but flame propagation into the nozzle is prevented
Solution Approach 1:
The patent segments the flow section into distinct zones: a flow constriction zone and an expansion section. This segmentation allows each zone to perform its specific function - the constriction promotes flame propagation into the nozzle while the expansion section maintains simple manufacturing characteristics, achieving both flame reliability and manufacturing ease
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 nozzle design effectively reduces NOx emissions by promoting flame propagation within the nozzle, enhancing combustion efficiency and extending the service life through controlled heat management and catalytic reactions.
Implementation Method 1
the flow section comprises a flow constriction with a, preferentially globally, minimal flow cross section, wherein the flow constriction is fluidically located between the inlet opening and the outlet opening
Implementation Method 2
the flow section has a flow cross section that continuously increases over the entire extension of the flow section from the flow constriction to the outlet opening
Implementation Method 3
facilitating fuel-rich combustion and reducing NOx formation
Data Source
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AI summary
The invention concerns a pulverized solid fuel, in particular coal, nozzle (10) comprising an inlet opening (12) for receiving a stream of coal/air mixture (16) and an outlet opening (14) for discharging said stream (16) into a burner. The inlet opening (12) and the outlet opening (14) are fluidically connected by a flow section (18), and a flow cross section (20) of the flow section (18) varies along a flow direction (22) of the stream of coal/air mixture (16). The flow section (18) comprises a flow constriction (24) with a, preferentially globally, minimal flow cross section (26). The flow constriction (24) is fluidically located between the inlet opening (12) and the outlet opening (14) and the flow section (18) has a flow cross section (20) that, in particular continuously, increases from the flow constriction (24) to the outlet opening (14).