Coanda Surface Cross-Lighting for LSV Burner Flame Stability
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Solution Overview
Problem
Fuel-staged burners face challenges in maintaining stable combustion and reducing NOx emissions, particularly during start-up, due to unstable flames and the need for pilots which increase NOx production and operational complexity.
Innovation Solution
The implementation of a Large Scale Vortex (LSV) burner system with a Coanda surface that directs fluid flow to cross-light fuel stage tips, eliminating the need for start-up lances and reducing NOx emissions by stabilizing the flame without additional flame-holding devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel is staged farther from the centerline to reduce NOx emissions, then combustion intensity is reduced and NOx production decreases, but flame stability deteriorates requiring pilot burners
Solution Approach 1:
A Coanda surface is introduced as an intermediary element that redirects the stabilized flame from the LSV toward the outer staged fuel tips. This mediator enables heat transfer and flame propagation to the distant fuel injection points without requiring additional pilot burners, thus maintaining flame stability while preserving the low NOx benefits of far-out fuel staging
Solution Approach 2:
The patent replaces the mechanical/pilot-based flame stabilization system with a fluid dynamic solution. Instead of using pilot burners or physical flame holders to stabilize the flame, the invention uses the Coanda effect and LSV fluid dynamics to achieve automatic flame stabilization and propagation to the staged fuel tips
2Reliability
If a continuous pilot is used to stabilize flame and enable cross lighting, then flame stability improves, but NOx emissions increase due to additional combustion
Solution Approach 1:
The invention extracts and eliminates the continuous pilot burner from the system. By using the LSV and Coanda surface combination, the patent removes the need for separate pilot combustion, thereby eliminating the source of additional NOx emissions while maintaining flame stability through fluid dynamic mechanisms
Solution Approach 2:
The LSV-flame stabilized on the Coanda surface serves its own flame propagation function. The stabilized flame automatically propagates to the staged fuel tips through the Coanda effect without requiring external pilot assistance, making the system self-sufficient and eliminating the need for separate pilot burners
3Productivity
If start-up lance is used to heat furnace during start-up, then heating capacity increases, but NOx emissions increase and device complexity increases
Solution Approach 1:
The invention extracts and removes the start-up lance component from the burner system. The LSV-flame combination provides sufficient heating capacity during start-up without requiring a separate high-capacity heating device, thereby eliminating the source of additional NOx emissions and reducing device complexity
Solution Approach 2:
The LSV-flame stabilization system performs multiple functions: it stabilizes the flame during normal operation, enables cross lighting to outer fuel tips, and provides sufficient heating capacity during start-up. This multi-functional approach eliminates the need for separate start-up lances and other auxiliary heating devices
4Reliability
If multiple components and control systems are added to accomplish cross lighting, then flame stability improves, but device complexity and operational risk increase
Solution Approach 1:
The patent replaces complex mechanical and control systems with a fluid dynamic solution. The Coanda effect and LSV fluid mechanics automatically achieve flame stabilization and propagation without requiring valves, controls, or multiple moving parts, thereby reducing device complexity while maintaining flame stability
Solution Approach 2:
The LSV-flame-Coanda surface system is self-regulating and self-propagating. The flame automatically stabilizes on the Coanda surface and self-propagates to the staged fuel tips through fluid dynamic forces, eliminating the need for external control systems, sensors, or automated controls
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 solution enhances flame stability, reduces NOx emissions, simplifies the burner design and operation, and allows for the use of inexpensive materials, while eliminating the need for complex start-up procedures and additional components, thereby improving reliability and reducing costs.
Implementation Method 1
a Coanda surface that directs fluid flow to cross-light fuel stage tips
Implementation Method 2
Large Scale Vortex (LSV) burner system with a Coanda surface that directs fluid flow to cross-light fuel stage tips, eliminating the need for start-up lances and reducing NOx emissions by stabilizing the flame
Data Source
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AI summary
A burner apparatus includes a fluid-based flame stabilizer for discharging a stabilized flame therefrom, a burner tile, and fuel lances associated with the burner tile. Each of the fuel lances has a discharge nozzle. A Coanda feature having an internal Coanda surface directs a portion of the stabilized flame from the passage defined by the burner tile at the discharge end of the primary flow passage toward at least one first fuel lance of the plurality of fuel lances to cross light the at least one first fuel lance. In another embodiment, a method of combustion includes supplying a first gaseous fuel to fuel lances of a burner apparatus and igniting and sustaining combustion of a gaseous fuel by cross lighting at the discharge nozzles of the fuel lances by flow from the fluid-based flame stabilizer along a Coanda surface of a Coanda feature toward the discharge nozzles.