Compact Burner Fluidic Flame Bending for Aluminum Scrap Melting
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Solution Overview
Problem
Existing scrap metal melting processes, particularly in secondary aluminum recycling, face inefficiencies in time, energy, and metal recovery due to high NOx formation and metal oxidation caused by high flame temperatures in oxy-combustion, leading to bulky and complex burner designs that are not effective at varying power levels.
Innovation Solution
A compact burner design that achieves distributed combustion by fluidically bending the flame using an actuating jet of oxidant and staging oxidant injection between primary and secondary portions, allowing for efficient melting and combustion at various power levels without visible flames, utilizing a dynamical fuel/oxidant nozzle and secondary lances to maintain low NOx production and uniform temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If oxy-combustion with high flame temperature is used to increase heat utilization, then thermal efficiency is improved, but NOx formation and metal oxidation increase significantly
Solution Approach 1:
The combustion process is segmented into multiple zones with different oxygen concentrations. The burner injects fuel and oxidant separately, creating a first combustion zone with high oxygen concentration for efficient heat generation, and a second combustion zone with lower oxygen concentration that reduces NOx formation. This spatial segmentation allows the system to achieve high thermal efficiency while controlling harmful emissions.
Solution Approach 2:
Different regions of the combustion chamber are provided with different oxygen concentrations and combustion intensities. The core combustion zone receives high oxygen concentration for maximum heat release, while peripheral zones receive diluted oxidant mixtures. This local differentiation enables high overall thermal efficiency while limiting peak temperatures that cause NOx formation and metal oxidation.
2Loss of energy
If oxy-combustion with high flame temperature is used, then thermal efficiency is improved, but metal oxidation rate increases resulting in metal losses
Solution Approach 1:
The combustion process is divided into zones with progressively diluted oxygen concentrations. The first zone provides intense heat for rapid melting, while subsequent zones with diluted oxidant maintain temperature without causing excessive metal oxidation. This segmented approach preserves metal recovery efficiency while achieving good thermal efficiency.
Solution Approach 2:
The oxygen concentration parameter is varied spatially and temporally during the combustion process. High oxygen concentration is applied initially for rapid heating and melting, then gradually reduced to lower levels that maintain thermal efficiency while minimizing metal oxidation. This dynamic parameter adjustment optimizes both energy efficiency and metal recovery.
3Object-generated harmful factors
If distributed combustion with diluted reactants is used to achieve lower and uniform temperatures, then NOx formation is reduced, but burner design becomes more complex
Solution Approach 1:
The burner combines multiple combustion zones and oxidant injection systems into a single integrated device. The fuel nozzle, primary oxidant injection, and secondary diluted oxidant injection are merged into one compact burner assembly. This integration achieves the benefits of distributed combustion for NOx reduction while keeping the overall burner design relatively simple and manageable.
4Loss of substance
If burner power is regulated to control metal oxidation during oxy-combustion, then metal losses are reduced, but time efficiency and productivity decrease
Solution Approach 1:
The combustion process is segmented into high-intensity and low-intensity zones that operate simultaneously. The high-intensity zone maintains high burner power for rapid melting and good productivity, while the low-intensity zone with diluted oxidant prevents excessive metal oxidation. This spatial segmentation allows the system to maintain high productivity while controlling metal losses.
Solution Approach 2:
Different local regions of the combustion chamber experience different oxygen concentrations and combustion intensities. The region near the charge experiences high heat flux for rapid melting, while surrounding regions have diluted combustion that limits oxidation. This local quality differentiation enables high productivity with controlled metal losses.
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 enhances melting efficiency, reduces NOx emissions, and maintains combustion stability across different power levels, resulting in a more compact and cost-effective burner that achieves optimal melting and combustion conditions for scrap metals like aluminum.
Implementation Method 1
initiating injection of a jet of a first actuating fluid downwards towards the jet of fuel and primary oxidant thereby impinging the jet of fuel and primary oxidant
Implementation Method 2
combustion with low concentrations of both fuel and oxygen in the furnace. Dilution of the reactants is obtained with spatially separated injections of them at high velocities
Implementation Method 3
The central idea of this strategy is to dilute the reactants with furnace gases (mostly mixture of H 2 O and CO 2 ) before combustion so as to achieve a lower and more uniform temperature distribution within the furnace
Implementation Method 4
Either one or both reactant jets are injected into the furnace in such a way as to facilitate entrainment of furnace gases into the jets
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A simple, compact burner achieves a more optimal melting of a solid charge followed by performance of combustion under distributed combustion conditions. The burner achieves this by fluidically bending the flame towards the solid charge during a melting phase with an actuating jet of oxidant, redirecting the flame in a direction away from the charge, and staging injection of oxidant among primary and secondary portions during a distributed combustion phase.