Burner Flame Formation Nitrogen Oxide Reduction
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Solution Overview
Problem
Existing burners for forming flames in furnaces face issues with nitrogen oxide generation and interference in flame formation due to the distribution of main combustion air, which is implemented by a deflector plate.
Innovation Solution
A burner design that incorporates a combustion head with a truncated cone shape and alternating ejector and air ducts, along with internal recirculation of flue gases, to efficiently stage combustion and reduce nitrogen oxide emissions by mixing flue gases with main gas, forming an inert return flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a deflector plate is used to distribute main combustion air for staging combustion, then combustion staging is achieved, but flame formation is interfered with and nitrogen oxide emissions increase
Solution Approach 1:
The harmful deflector plate is completely removed from the combustion head. Instead of using a deflector plate to distribute combustion air, the invention uses a simplified combustion head geometry with air supply channels that direct air flow without mechanical interference, thereby eliminating both the interference with flame formation and the associated nitrogen oxide emissions
Solution Approach 2:
The patent introduces flue gas recirculation as an intermediary substance to achieve combustion staging. By mixing recirculated flue gas with fresh combustion air through air supply channels, the system achieves staged combustion without needing a deflector plate, thus avoiding flame interference while maintaining combustion efficiency and reducing nitrogen oxide emissions
2Object-generated harmful factors
If flue gases are recirculated to reduce nitrogen oxides, then nitrogen oxide emissions decrease, but combustion stability may be affected
Solution Approach 1:
The patent carefully controls the parameters of flue gas recirculation, including the recirculation ratio and mixing position. By optimizing these parameters, the system achieves sufficient nitrogen oxide reduction while maintaining combustion stability through proper air-fuel ratio control and flame zone temperature management
3Ease of manufacture
If the combustion head is simplified without a deflector plate, then manufacturing cost decreases, but combustion air distribution control is reduced
Solution Approach 1:
The mechanical deflector plate system is replaced with a streamlined air supply channel design that uses fluid dynamics and geometric configuration to control air distribution. This substitution simplifies manufacturing while maintaining effective combustion air distribution through optimized channel shapes and positions
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 design achieves nitrogen oxide emissions lower than 2.5 ppm without external recirculation, with an inert return flow containing less than 5000 ppm of carbon monoxide and methane, and maintains a maximum temperature of the air-flue gas mixture below 500°C.
Implementation Method 1
a number of ejector ducts provided for recirculating flue gas from the furnace to the gaseous fuel from the main gas rods
Implementation Method 2
mixing flue gases with main gas, forming an inert return flow
Implementation Method 3
for forming a flame in a furnace by means of gaseous fuel and combustion air
Data Source
Figure 1~3
Figure 2A
Figure 2B~2C
AI summary
The invention relates to a burner (1) for forming a flame (F) in a furnace (3) by means of gaseous fuel (G) and combustion air (I), simultaneously recirculating flue gases (S) in the furnace (3), wherein the burner (1) comprises - a burner frame (1a) and a combustion head (2) connected to the same by its cylindrical body (20), wherein the end portion (21) of the combustion head (2) facing the furnace (3) extends at its first end to the furnace (3), and the second end of the end portion (21) is connected to said cylindrical body (20), - a primary gas pipe (10) for supplying gaseous fuel (G; G1) to the furnace (3), wherein the primary gas pipe (10) extends inside the combustion head (2) in its longitudinal direction, particularly inside (T) of the end portion (21) of the combustion head, and the orifice of the primary gas pipe (10) opens into or close to the furnace (3), and a primary air supply pipe (14) also extends inside the combustion head (2) and surrounds said primary gas pipe (10), and the orifice of the supply pipe (14) opens into the furnace (3) or to the orifice (21) of the end portion (21) of the combustion head (2), - a flow duct for main combustion air (Imain) extending inside the combustion head and surrounding said primary air supply pipe (14) at least inside (T) of the end portion (21), and - a set of main gas rods (6), comprising a set of elongated primary gas rods (61, 62... 6n) extending in the longitudinal direction of the combustion head, for supplying the furnace (3) with fuel, wherein the main gas rods (61, 62... 6n) are arranged at least partly outside the cylindrical body (20) of the combustion head (2), extending close to the joint (L) between the cylindrical body (20) and the end portion (21) so that they are surround said body (20) at regular intervals around the circumference of the body (20), and wherein in connection with the main gas rods (6', 62.. 6n), at the end portion (21) of the combustion head, several ejector ducts (8; 81) are provided for recirculating flue gas (S) from the furnace (3) into the gaseous fuel (G; G2) coming from the main gas rods, and for conveying the produced flue gas-flue mixture (S+G2) further to the furnace (3).