Perforated Flame Holders for Stable Lean Combustion
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Solution Overview
Problem
Industrial burner systems face challenges in efficiently managing combustion reactions, particularly in supporting leaner fuel-to-oxidant mixtures and minimizing nitrogen oxides (NOx) emissions, as conventional flame holders struggle to maintain stable combustion under these conditions.
Innovation Solution
The burner system employs perforated flame holders with multiple apertures to contain and heat the combustion reaction, using a master fuel valve and controller to regulate fuel flow based on system parameters, and incorporates a method to selectively activate and control the number of fuel nozzles for precise heat generation, while utilizing a preheat mode to elevate the flame holder temperature for stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional flame holders are used to support combustion, then stable combustion can be maintained, but the ability to support leaner fuel-to-oxidant mixtures is limited and NOx emissions increase
Solution Approach 1:
The flame holder is divided into multiple segments with separate aperture openings, allowing independent control of fuel flow to different zones. This segmentation enables the burner to support leaner mixtures by directing fuel to specific segments while maintaining stable combustion, thereby reducing NOx emissions without sacrificing combustion stability.
Solution Approach 2:
Different zones or segments of the flame holder are designed with different aperture configurations and local properties to optimize fuel distribution. By applying local quality variations, the system can support leaner fuel-to-oxidant mixtures in specific regions while maintaining stable combustion, thus reducing overall NOx emissions.
2Adaptability or versatility
If multiple fuel nozzles are used to control heat output, then flexible heat generation is achieved, but system complexity increases
Solution Approach 1:
Multiple fuel nozzles are merged into a single integrated burner assembly with a unified control system. This merging approach allows flexible heat output control by adjusting the collective flow through multiple nozzles while reducing the number of separate control elements, thus achieving adaptability without proportionally increasing system complexity.
Solution Approach 2:
The burner system is designed as a multi-functional unit where the same structure serves multiple purposes: fuel distribution, flame stabilization, and heat output control. By applying universality, the system achieves flexible heat generation capability while minimizing the need for separate specialized components, thereby reducing overall device complexity.
3Power
If high-temperature combustion is used to generate heat, then heat output is increased, but NOx emissions increase due to high-temperature exposure of combustion fluids
Solution Approach 1:
The combustion process is segmented into multiple zones with different temperature profiles. By directing fuel flow to specific segments, the system maintains high heat output in certain zones while allowing other zones to operate at lower temperatures, thus reducing overall NOx formation while preserving total power output.
Solution Approach 2:
The system dynamically changes combustion parameters such as fuel flow rate, air-to-fuel ratio, and residence time to optimize the balance between heat output and NOx emissions. By adjusting these parameters, the burner can maintain high power generation while limiting the temperature exposure of combustion fluids that leads to NOx formation.
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 configuration allows for stable combustion with leaner fuel-to-oxidant mixtures, reduces NOx emissions by limiting high-temperature exposure of combustion fluids, and enables flexible heat output control, enhancing operational efficiency and reducing environmental impact.
Implementation Method 1
holding a flame substantially between its first and second faces during a heating operation
Implementation Method 2
transmitting heat generated by the flames to a heat-receiving structure
Implementation Method 3
a master fuel valve coupled to each of the plurality of nozzles and configured to separately regulate a flow of fuel to each of the nozzles
Implementation Method 4
a plurality of heat exchange tubes positioned in a circular configuration, substantially concentric with the cylindrically shaped combustion chamber
Implementation Method 5
transmitting heat generated by the flames to a heat-receiving structure
Data Source
AI summary
A burner system includes a plurality of burners, each having a nozzle positioned to emit a stream of fuel into a combustion volume, and a perforated flame holder, including a plurality of apertures extending between first and second faces thereof, and positioned to receive a stream of fuel from the respective nozzle. In operation, the flame holders are configured to hold a flame substantially within the plurality of apertures.