Oscillating Burner Layout for Uniform Heating and Low NOx
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Solution Overview
Problem
In direct-firing type heating furnaces used in iron production, surface oxidation of intermediate products leads to yield reduction 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 a center fluid ejection outlet and multiple peripheral fluid ejection outlets arranged at optimized positions to facilitate balanced mixing of fuel and combustion gases, promoting self-induced oscillation and maintaining high 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, enabling the flame to periodically change its orientation and sweep across a wider area. This dynamic behavior allows the burner to maintain high heat transfer efficiency while reducing localized surface oxidation, as the flame does not continuously impinge on a single spot on the intermediate product.
Solution Approach 2:
The burner utilizes periodic oscillation of the flame at optimized frequencies to achieve uniform heat distribution. The flame periodically changes direction, creating a sweeping motion that distributes thermal energy more evenly across the intermediate product surface, thereby reducing surface oxidation while maintaining overall heat transfer efficiency.
2Productivity
If oxygen-enriched combustion is performed to improve heating efficiency, then NOx emissions increase
Solution Approach 1:
The self-induced oscillation creates dynamic combustion conditions that periodically vary the oxygen-fuel mixing ratio and flame temperature. This dynamic behavior prevents sustained high-temperature zones that would otherwise lead to excessive NOx formation, while still maintaining high overall heating efficiency through improved heat distribution.
Solution Approach 2:
The periodic oscillation of the flame introduces cyclic variations in combustion intensity and temperature distribution. This periodic action allows for more complete combustion (improving heating efficiency) while the varying conditions prevent the formation of persistent high-temperature zones that generate excessive NOx emissions.
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 larger effective heating area by periodically changing the flame direction. This dynamic sweeping action allows one burner to uniformly heat long intermediate products, replacing the need for multiple burners and reducing apparatus cost while maintaining heating uniformity.
Solution Approach 2:
The periodic oscillation of the flame creates a time-varying heat distribution pattern that, when integrated over time, results in uniform heating across the entire intermediate product. The flame sweeps back and forth, ensuring all areas receive adequate thermal energy, thereby achieving the heating uniformity that would otherwise require multiple burners.
4Manufacturing precision
If multiple burners are arranged in parallel to heat long intermediate products uniformly, then heating uniformity is improved, but apparatus cost increases
Solution Approach 1:
The self-induced oscillation transforms a single stationary burner into a dynamically effective multiple-burner system. The oscillating flame covers a wider area and provides more uniform heating, replacing the need for multiple burners arranged in parallel, thereby reducing apparatus cost while maintaining heating uniformity.
Solution Approach 2:
The periodic oscillation allows one burner to perform the heating function that would otherwise require multiple burners. By sweeping the flame across the intermediate product surface in a periodic manner, a single burner achieves the uniform heating distribution that multiple static burners would provide, reducing equipment cost.
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, thereby enhancing the yield and reducing apparatus costs.
Implementation Method 1
a self-induced oscillation phenomenon in which a jet flow periodically changes
Implementation Method 2
the intermediate product is heated by radiant heat transfer of the flame
Implementation Method 3
mix the fuel gas and the combustion-supporting gas with an optimal balance between the flow rate and the flow velocity
Data Source
Figure 1
Figure 2
Figure 3(A)~3(B)
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.