Movable Burner Nozzle for NOx Reduction and Temperature Control
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Solution Overview
Problem
Existing combustion devices face challenges in reducing NOx concentration in exhaust gases while maintaining design temperatures of rear heat transfer surfaces, and complex arrangements are required for burners with multiple air inflow directions.
Innovation Solution
A combustion device with multiple burners featuring cylindrical fuel and combustion gas nozzles, a wind box with adjustable flow rate, and a duct system that allows for independent adjustment of combustion gas flow rates to deflect flames and optimize thermal absorption, reducing NOx concentration and simplifying the combustion gas supply system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the after-air port is installed at a high position of the furnace to increase detention time, then NOx concentration in exhaust gas is reduced, but the complete combustion region shifts downstream and exhaust gas temperature at the furnace outlet increases
Solution Approach 1:
The burner is designed with movable nozzles that can dynamically adjust the combustion region position. The nozzle can move between a first position for normal combustion and a second position to shift the combustion region upstream, allowing flexible adaptation to different operational conditions and resolving the contradiction between NOx reduction and temperature control
Solution Approach 2:
The invention changes the spatial position parameter of the combustion region by moving the nozzle. This parameter change allows the combustion region to be positioned at different locations within the furnace, enabling optimization of both NOx reduction (through increased detention time) and temperature control (by preventing excessive downstream shift)
2Object-generated harmful factors
If the excess air ratio is lowered to reduce thermal NOx, then NOx emission is reduced, but the combustion temperature rises and exhaust gas temperature at the furnace outlet increases
Solution Approach 1:
The movable nozzle allows dynamic adjustment of the combustion region position to compensate for temperature changes. When excess air ratio is lowered, the nozzle can be positioned to optimize combustion temperature distribution, preventing excessive temperature rise while maintaining low NOx emission levels
Solution Approach 2:
The system allows operational adjustment of combustion parameters including excess air ratio and nozzle position. This feedback mechanism enables optimization of the balance between NOx reduction (through lower excess air ratio) and temperature control (through nozzle positioning) based on actual combustion conditions
3Object-generated harmful factors
If the burner flame direction is changed to downward to increase detention time in NOx reduction region, then NOx concentration is reduced, but the arrangement of combustion air flow paths becomes complicated
Solution Approach 1:
Multiple combustion air nozzles are integrated into a single unified structure with a common air supply system. This merging approach simplifies the overall arrangement by consolidating what would otherwise be separate complex flow path arrangements into a coordinated system that achieves flame direction control without excessive complexity
4Adaptability or versatility
If a movable nozzle is used to adjust combustion region position, then flame direction can be changed, but damage from falling clinkers and securement of movability become concerns
Solution Approach 1:
The nozzle is designed with movable components that can be positioned and locked in specific locations. This dynamic design allows flame direction adjustment while incorporating locking mechanisms and protective structures that prevent damage from falling clinkers and ensure reliable operation in the harsh furnace environment
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 solution effectively reduces NOx concentration in exhaust gases, maintains optimal heat transfer surface temperatures, and simplifies the combustion gas supply system by allowing for independent adjustment of combustion gas flow rates, enhancing both NOx reduction and thermal management.
Implementation Method 1
the wind box (12) has a combustion gas inflow opening portion (12a, 12b) into which the combustion gas flows from one direction and is partitioned to form a plurality of parallel flow paths
Implementation Method 2
one or more cylindrical combustion gas nozzles (8, 11) which are provided on the outer circumference of the fuel nozzle (3) and inject a combustion gas into the furnace (18)
Implementation Method 3
a cylindrical fuel nozzle (3) which injects a mixture of a fuel and a carrier gas therefor into the furnace (18)
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
Provided is a boiler having plurality of burners (19) arranged on a furnace wall (10) of a furnace (18), each burner (19) comprising: a cylindrical fuel nozzle (3) for injecting a mixture of fuel and carrier gas therefor into the furnace (18); one or more cylindrical air nozzles (8, 11) provided on the outer circumference of the nozzle (3) for injecting combustion air into the furnace, and a wind box (12) for supplying combustion air to the nozzles (8, 11) in common. The wind box (12) is provided with openings (12a, 12b) through which combustion air flows in from one direction perpendicular to the axial direction of the burner (19), and is partitioned by a partition wall (14) to form plurality of parallel flow paths for the air flowing in through the openings. Some of the plurality of flow paths are connected to an upper part of the combustion air nozzle (8), and the other flow paths are connected to a lower part of the nozzle (8). Each of the plurality of combustion air flow paths is independently provided with an air momentum deviation damper (15) and an air flow rate adjustment damper (17), such that the direction of the flame of the burner (19) can be changed between upward and downward directions inside the furnace (18) depending on a combustion condition such as a load.