Adjustable Fuel Nozzle for Perforated Flame Holder Combustion
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Solution Overview
Problem
Conventional combustion systems face challenges in achieving stable and clean combustion, particularly in reducing NOx emissions and maintaining combustion under lean fuel-to-oxidant ratios, often requiring additional measures like selective catalytic reduction or external flue gas recirculation.
Innovation Solution
The implementation of a combustion system featuring a perforated flame holder with an adjustable-position fuel nozzle, which preheats the flame holder to a threshold temperature using a startup flame and then retracts to support a stable combustion reaction, allowing for efficient mixing and reduced peak flame temperatures, thereby minimizing NOx production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional combustion systems operate with lean fuel-to-oxidant ratios, then fuel efficiency is improved, but NOx emissions increase due to high peak flame temperatures
Solution Approach 1:
The system performs preliminary heating of the flame holder to a threshold temperature using a startup flame before introducing the main fuel flow. This preheating action enables the flame holder to immediately support stable combustion of lean mixtures without requiring high peak temperatures, thus achieving fuel efficiency while minimizing NOx emissions
Solution Approach 2:
The system changes the thermal state parameter of the flame holder by heating it to a threshold temperature before combustion. This parameter change allows the flame holder to maintain stable combustion at lower peak temperatures, enabling lean fuel-to-oxidant ratios without producing excessive NOx
2Reliability
If the fuel nozzle is positioned close to the perforated flame holder, then stable combustion is achieved, but the system cannot maintain stable combustion across varying operating conditions
Solution Approach 1:
The fuel nozzle is made movable rather than fixed, allowing its position to be dynamically adjusted relative to the perforated flame holder. This enables the system to adapt the nozzle-to-flame-holder distance based on varying operating conditions while maintaining stable combustion, thus achieving both reliability and adaptability
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 achieves low NOx emissions (down to undetectable levels) and complete combustion of CO, supporting combustion with lean fuel-to-oxidant ratios without the need for additional pollution control measures, while maintaining stable combustion reactions within the perforated flame holder.
Implementation Method 1
preheating a perforated flame holder to a threshold temperature by supporting a preheating flame of the first flow of fuel near the perforated flame holder
Implementation Method 2
supporting a combustion reaction of the fuel and oxidant mixture within the perforated flame holder
Data Source
AI summary
A method for a combustion system includes outputting fuel from an adjustable-position fuel nozzle onto a perforated flame holder, the fuel being directed for mixture with an oxidant en route to the perforated flame holder. A combustion reaction of the fuel and the oxidant is supported within the perforated flame holder. A position of the adjustable-position fuel nozzle may be changed relative to the flame holder. A first flow of fuel may be output when the adjustable position fuel nozzle is in an extended state, and a second flow of fuel may be output when the adjustable-position fuel nozzle is in a retracted state.