Oscillating Burner Nozzle Layout for Uniform Low-NOx Heating
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Solution Overview
Problem
In direct-firing type heating furnaces used in iron production, surface oxidation of intermediate products leads to reduced yield due to oxygen in combustion gases, and conventional burners have low radiant heat transfer efficiency, resulting in uneven heating and increased NOx emissions.
Innovation Solution
A burner design with multiple fluid ejection outlets, including a center outlet and peripheral outlets arranged to optimize gas flow and mixing, allowing for self-induced oscillation to enhance combustion balance and heat transfer efficiency while reducing NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional burner is arranged in parallel to the intermediate product for radiant heat transfer, then surface oxidation is reduced, but heat transfer efficiency is lowered
Solution Approach 1:
The burner employs self-induced oscillation to dynamically adjust the flame direction periodically, allowing the flame to alternately point toward and away from the intermediate product. This dynamic adjustment optimizes both radiant heat transfer to the product surface and mixing between fuel gas and combustion-supporting gas, resolving the contradiction between heat transfer efficiency and oxidation control
2Loss of energy
If oxygen-enriched combustion is performed to improve heat transfer efficiency, then heating efficiency increases, but NOx emissions increase
Solution Approach 1:
The self-induced oscillation creates periodic action in the combustion process, where the flame direction alternates between pointing toward and away from the intermediate product. This periodic movement enhances mixing between oxygen-enriched combustion gas and fuel gas during the oscillation cycle, improving combustion efficiency while controlling NOx formation through optimized mixing rather than continuous high-temperature combustion
3Device complexity
If a single burner is used with a long intermediate product, then apparatus cost is reduced, but heating uniformity deteriorates
Solution Approach 1:
The self-induced oscillation enables a single burner to dynamically cover a wider heating area by periodically changing the flame direction. This dynamic adjustment allows one burner to effectively heat long intermediate products uniformly, replacing the need for multiple burners and reducing apparatus complexity while maintaining heating uniformity
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 achieves uniform heating with improved heat transfer efficiency and reduced NOx emissions, even when heating objects away from the center axis, by optimizing the arrangement and flow rates of gas ejection outlets, thus addressing the challenges of surface oxidation and uneven heating in direct-firing furnaces.
Implementation Method 1
it has been proposed to oscillate the flame by using a so-called self-induced oscillation phenomenon of a jet flow
Implementation Method 2
the intermediate product is heated by radiant heat transfer of the flame
Implementation Method 3
a nozzle structure that applies a self-induced oscillation phenomenon in which the jet flow periodically changes
Implementation Method 4
burns them
Data Source
AI summary
The object of the present invention is to provide a burner which is capable of decreasing the amount of NOx emission and heating the object to be heated uniformly with excellent heat transfer efficiency when heating the object to be heated while oscillating the flame by self-induced oscillation, and a method for heating using a burner, and the present invention provides a burner including a center fluid ejection outlet 2 having a sectional fan shape in which an interval between a pair of side walls 63a and 63b gradually expands toward a downstream side, a pair of openings 62a and 62b provided on side walls 61 of a fluid ejection flow path 6 on an upstream side of the central fluid ejection port 2 and communicated by a communication pipe 7, a first peripheral fluid ejection outlet arranged around the center fluid ejection outlet, a second peripheral fluid ejection outlet is arranged at a position at which a distance between a center thereof and a center of the center fluid ejection outlet is larger than a distance between a center of the first peripheral fluid ejection outlet and the center of the center fluid ejection outlet, and in a direction orthogonal to an expanding direction of the center fluid ejection outlet, and a third peripheral fluid ejection outlet is arranged at a position at which a distance between a center thereof and the center of the center fluid ejection outlet is larger than the distance between the center of the second peripheral fluid ejection outlet and the center of the center fluid ejection outlet, and in the direction orthogonal to the expanding direction of the center fluid ejection outlet.