Burner Pre-Chamber Parallel Injection for NOx Reduction
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Solution Overview
Problem
Standard burners in industrial furnaces, particularly in indurating furnaces of pelletizing plants, produce high NOx emissions due to high combustion air temperatures, leading to environmental issues and potential thermal damages, and existing methods for reducing NOx emissions are either costly or insufficiently effective.
Innovation Solution
A burner assembly with a pre-chamber that supplies fuel, cold primary air, and preheated air, where the preheated air is injected parallel to the fuel and primary air, reducing peak temperatures and NOx formation by diluting the fuel mixture before it enters the main combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If standard burners are used with high combustion air temperature, then efficient combustion is achieved, but NOx emissions increase and thermal damages occur
Solution Approach 1:
The combustion process is segmented into two distinct chambers: a pre-chamber where fuel and primary air are mixed and ignited, and a main combustion chamber where preheated combustion air is introduced. This segmentation allows the combustion to occur in stages, reducing peak temperatures and NOx formation in the main chamber while maintaining efficient combustion in the pre-chamber.
Solution Approach 2:
The pre-chamber acts as an intermediary between the fuel injection system and the main combustion chamber. It pre-mixes fuel and primary air, ignites the mixture, and then introduces the partially combusted gases into the main combustion chamber, where preheated combustion air is added to complete the combustion process with lower peak temperatures.
2Use of energy by moving object
If high combustion air temperature is used, then combustion efficiency improves, but thermal damages to combustion chamber wall increase
Solution Approach 1:
The combustion chamber is divided into a pre-chamber and a main combustion chamber. The pre-chamber handles the initial high-temperature combustion, while the main combustion chamber receives preheated air at controlled temperatures, reducing thermal stress on the chamber walls.
Solution Approach 2:
The temperature of the combustion air is changed by preheating it before introduction to the main combustion chamber. This parameter change allows efficient combustion while controlling the peak temperature to reduce thermal damages to the combustion chamber wall.
3Object-generated harmful factors
If air-staged combustion is used to reduce NOx, then NOx emissions decrease, but device complexity increases
Solution Approach 1:
The combustion system is segmented into a pre-chamber and a main combustion chamber with distinct air and fuel injection systems. This segmentation enables air-staged combustion where primary air is supplied to the pre-chamber and preheated combustion air is supplied to the main chamber, reducing NOx emissions through controlled combustion stages.
Solution Approach 2:
The pre-chamber is nested within or adjacent to the main combustion chamber, with the pre-chamber handling the initial combustion and the main chamber completing the process. This nested arrangement allows for reduced NOx emissions while maintaining a relatively compact and integrated device structure.
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 approach significantly reduces the need for primary air and achieves lower NOx emissions compared to air-staged combustion methods, while maintaining efficient combustion and reducing thermal stress on the combustion chamber.
Implementation Method 1
the trajectories of the streams are basically determined by the shape and orientation of the corresponding inlets... mixing progresses further into the streams core
Implementation Method 2
shear induced turbulence production only occurs in the outer shell of each injection stream
Implementation Method 3
the combustion of the fuel whereby combustion heat is developed
Implementation Method 4
ignition of the fuel, the combustion of the fuel and the transfer of combustion heat
Implementation Method 5
the transfer of combustion heat to the first medium that is present at the combustion arrangement
Implementation Method 6
transfer of combustion heat to the first medium
Implementation Method 7
The preheated combustion air is entrained by the streams (fuel, primary and preheated air) injected parallel into the pre-chamber
Implementation Method 8
the trajectories of the streams are basically determined by the shape and orientation of the corresponding inlets
Data Source
Figure 1~2
Figure 3
AI summary
The above mentioned invention describes a method for combustion of gaseous or liquid fuel using a burner assembly (1). Therein fuel, cold primary air and preheated air are supplied to a pre-chamber (2), whereby the fuel and cold primary air being supplied through at least one fuel feed (4) and at least one primary air feed (5), and preheated combustion air is supplied to a combustion chamber (3). The preheated air and/or the cold primary air are injected parallel to the fuel into the pre-chamber (2).