Low NOx Premixed Hydrogen Burner Plenum Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hydrogen burners using the premixing method face challenges in reducing NOx emissions and maintaining stable combustion due to high flame temperatures, backfire, and misfire issues.
Innovation Solution
A low NOx premixed hydrogen burner design featuring a plenum chamber with a specific length-to-radius ratio, combined with outer and inner cooling air supply pipes, enhances gas mixing, stabilizes combustion, and reduces NOx generation by cooling the premixed flame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the premixing method is used for hydrogen combustion, then the flame temperature is reduced and NOx emissions are lowered, but the stable operation area is limited due to backfire and misfire
Solution Approach 1:
The burner is divided into multiple functional zones: a mixing zone where hydrogen and air are premixed, a combustion zone where stable flame occurs, and a cooling zone where flame temperature is controlled. The plenum chamber segments the flow path to ensure proper mixing before combustion, while the cooling air supply segments the thermal field to prevent excessive temperatures that cause backfire and misfire.
Solution Approach 2:
Different regions of the burner are given different properties: the plenum chamber provides a large mixing volume with specific length-to-diameter ratio for thorough mixing, the outlet pipe provides focused flame formation, and the cooling air supply pipes provide localized cooling at critical positions. The outer cooling air supplies cool to the flame periphery while inner cooling air cools the central region, creating a controlled temperature gradient that expands the stable operation range.
2Stability of the object's composition
If the plenum chamber diameter is increased to improve gas mixing, then the mixing efficiency is enhanced, but the device size increases
Solution Approach 1:
The plenum chamber is designed with a specific length-to-diameter ratio (6.7-6.9) that optimizes mixing efficiency while controlling size. The diameter is set to be two times or more than the upstream pipe diameter, which provides sufficient mixing volume without excessive enlargement. The outlet pipe diameter is carefully controlled to balance flame stability and device compactness.
Solution Approach 2:
The inner cooling air supply pipe is nested within the plenum chamber, extending through its interior to the outlet pipe. This nested arrangement allows the cooling function to be integrated into the existing structure without adding external volume, thereby improving gas mixing and cooling efficiency while maintaining a compact overall burner size.
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
The burner effectively reduces NOx emissions and expands the stable combustion operation range by improving gas mixing and cooling the flame, thereby reducing exposure time to high-temperature areas.
Implementation Method 1
a plenum chamber (10) including an inlet pipe (12) and an outlet pipe (14) and configured to mix hydrogen and combustion air introduced through the inlet pipe (12) to generate premixed gas for flame formation
Implementation Method 2
an outer cooling air supply pipe (40) connected to the outlet pipe (14) of the plenum chamber (10), and configured to flow outer cooling air along an outer periphery of the outlet pipe (14) to cool the premixed gas discharged from the plenum chamber (10)
Implementation Method 3
an inner cooling air supply pipe (50) installed to extend through an interior of the plenum chamber (10) to the outlet pipe (14) of the plenum chamber (10), and configured to flow inner cooling air to cool the premixed gas in the plenum chamber (10)
Implementation Method 4
The burner effectively reduces NOx emissions and expands the stable combustion operation range by improving gas mixing and cooling the flame, thereby reducing exposure time to high-temperature areas
Data Source
AI summary
Disclosed is a low NOx premixed hydrogen burner including: a plenum chamber including an inlet pipe and an outlet pipe and for mixing hydrogen and combustion air introduced through said inlet pipe to generate premixed gas for flame formation, in which a diameter of said plenum chamber is larger than diameters of said inlet pipe and the outlet pipe, and a length of said plenum chamber is greater than the diameter of said plenum chamber.