Perforated Reaction Holder for Low-NOx Fuel Combustion
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Solution Overview
Problem
Industrial and commercial burners produce significant air pollution, including NOx and CO, and suffer from uncontrolled flame conformation and high peak temperatures leading to operational issues like coking and uneven heating.
Innovation Solution
A burner system equipped with a perforated reaction holder that supports lean combustion, minimizing peak flame temperature and residence time by containing the combustion reaction within perforations, using a refractory material to manage heat and stabilize the flame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional combustion systems are used, then combustion reaction is relatively uncontrolled and flame conformation varies, but this causes high peak temperatures and long residence times leading to increased NOx and CO emissions
Solution Approach 1:
The invention employs a porous reaction holder made of high-temperature-resistant material with controlled porosity (30-70% void fraction) to support and control the combustion reaction. The porous structure provides numerous flow paths that distribute the fuel-air mixture uniformly, ensuring complete combustion while maintaining peak temperatures below 1500°F to reduce NOx formation and eliminate CO emissions.
Solution Approach 2:
The invention changes key combustion parameters by using a porous reaction holder to control the combustion zone geometry and temperature distribution. By adjusting the porosity (30-70% void fraction) and pore size (0.002-0.5 inches) of the reaction holder, the system achieves complete combustion with peak temperatures limited to below 1500°F, thereby reducing NOx emissions while maintaining zero CO emissions.
2Productivity
If conventional burners are used, then combustion is uncontrolled, but this leads to operational issues such as coking of reaction tubes and uneven heating of steam tubes
Solution Approach 1:
The porous reaction holder with controlled void fraction (30-70%) provides uniform distribution of fuel-air mixture throughout the combustion zone, ensuring even heat transfer to surrounding steam tubes and preventing localized overheating. This uniform combustion pattern eliminates coking of reaction tubes while maintaining high combustion efficiency.
Solution Approach 2:
The system incorporates temperature monitoring and control mechanisms that provide feedback to maintain peak combustion temperatures below 1500°F. This feedback control ensures consistent combustion conditions, preventing operational issues such as coking and uneven heating while maintaining high productivity.
3Object-generated harmful factors
If lean combustion is used to reduce NOx, then peak flame temperature is minimized, but this requires precise control of fuel-to-air ratio which is difficult to maintain
Solution Approach 1:
The porous reaction holder with controlled porosity (30-70% void fraction) provides inherent mixing and distribution of fuel-air mixture, eliminating the need for complex external control systems. The porous structure naturally ensures complete combustion at lean ratios by distributing the mixture uniformly throughout the combustion zone, thereby reducing NOx emissions without increasing control complexity.
Solution Approach 2:
The porous reaction holder performs the mixing and distribution function that would otherwise require complex external control systems. The structure itself provides the fuel-air mixture distribution through its porous network, enabling lean combustion to proceed automatically without additional control mechanisms, thus reducing NOx emissions while maintaining simple operation.
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
Reduces NOx output to low single-digit parts per million and stabilizes the flame, improving operational efficiency and reducing pollutants.
Implementation Method 1
supports a fuel combustion reaction supported by the fuel and oxidant mixture in the perforations
Implementation Method 2
using a refractory material to manage heat and stabilize the flame
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A combustion system such as a furnace or boiler includes a perforated reaction holder configured to hold a combustion reaction that produces very low oxides of nitrogen (NOx).