Coanda Gas Burner Tile for Low NOx Emissions
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Solution Overview
Problem
Existing gas burners face challenges in reducing nitrous oxide and carbon monoxide emissions while maintaining flame stability, as excessive dilution of fuel gas can lead to non-combustibility and instability, and current technologies lack efficient methods for incorporating flue gas to achieve this reduction.
Innovation Solution
The integration of Coanda surfaces within the burner tile to enhance mixing of fuel gas with air and flue gas, allowing for increased flue gas incorporation without diluting the fuel gas to a point of non-combustibility, thereby stabilizing the flame and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If flue gas is incorporated to reduce nitrous oxide formation, then emissions are reduced, but flame stability deteriorates due to excessive dilution
Solution Approach 1:
The combustion process is divided into multiple zones: a primary combustion zone where fuel gas mixes with air and burns, and a secondary zone where flue gas is introduced to further reduce NOx. This segmentation allows controlled dilution in specific regions without compromising overall flame stability.
Solution Approach 2:
Flue gas dilution is applied locally in specific regions rather than uniformly throughout the combustion process. TheCoanda surfaces enable targeted introduction of flue gas at specific locations where it most effectively reduces NOx emissions without causing widespread flame instability.
2Object-generated harmful factors
If fuel gas is diluted with air and flue gas to reduce combustion temperature, then nitrous oxide formation is reduced, but combustion efficiency deteriorates
Solution Approach 1:
Air and fuel gas are pre-mixed in controlled proportions before combustion occurs. This preliminary mixing ensures optimal combustion conditions are established before flue gas dilution takes place, maintaining combustion efficiency while enabling subsequent NOx reduction through controlled dilution.
Solution Approach 2:
The composition and temperature parameters of the combustion mixture are dynamically adjusted by controlling the ratios of fuel gas, air, and flue gas. This allows optimization of both combustion efficiency and NOx emissions by finding the right parameter balance.
3Quantity of substance
If Coanda surfaces are used to enhance mixing, then flue gas incorporation is increased, but device complexity increases
Solution Approach 1:
The Coanda surfaces utilize the natural Coanda effect, where a fluid jet automatically adheres to and follows a curved surface without external control mechanisms. This self-service principle enables enhanced flue gas mixing and incorporation through passive geometric features rather than active control systems, minimizing added complexity.
Solution Approach 2:
Coanda surfaces employ curved geometries that naturally guide and enhance the mixing of flue gas with the combustion stream. The curvature of these surfaces creates the necessary fluid dynamics effects to increase flue gas incorporation without requiring complex mechanical or electronic systems.
Data Source
Figure 1
Figure 2~3
Figure 3A~4A
AI summary
A gas burner apparatus for discharging a mixture of fuel gas, air and flue gas into a furnace space of a furnace wherein the mixture is burned and flue gas having a low content of nitrous oxides and carbon monoxide is formed is provided. The burner tile includes at least one gas circulation port extending though the wall of the tile. The interior surface of the wall of the tile includes a Coanda surface. Fuel gas and/or flue gas conducted through the gas circulation port follows the path of the Coanda surface which allows more flue gas to be introduced into the stream. The exterior surface of the wall of the tile also includes a Coanda surface for facilitating the creation of a staged combustion zone. Also provided are improved burner tiles, improved gas tips and methods of burning a mixture of air, fuel gas and flue gas in a furnace space.