Wide-Flame Oxy-Solid Fuel Burner Flame Stability
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Solution Overview
Problem
Solid fuels like petroleum coke and anthracite coal are difficult to ignite in a flowing stream due to low volatile matter content, leading to unstable combustion conditions and high unburned carbon levels, as existing flat-flame burners are not configured to handle solid fuels effectively.
Innovation Solution
A flat flame burner design featuring a fuel nozzle with guide vanes forming a combination diffuser/converging nozzle and a flow segregator, along with primary oxygen introduction through an annulus, creates a recirculation pattern that stabilizes the combustion of pulverized solid fuels by controlling fuel stream velocities and oxygen distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If solid fuel is combusted in a flowing stream, then the flame can be maintained continuously, but the flame front becomes detached from the fuel nozzle due to ignition delay
Solution Approach 1:
The burner introduces oxygen in advance of the fuel stream through annular passages and recirculation zones, creating a pre-heated oxygen-rich environment that reduces ignition delay and enables the flame front to attach to the fuel nozzle while maintaining continuous combustion
2Loss of time
If the flame front is detached from the fuel nozzle, then ignition delay is reduced, but unburned carbon increases and combustion becomes unstable
Solution Approach 1:
The burner creates a recirculation zone that returns hot combustion products and partially burnt fuel back to the combustion zone, providing thermal feedback that maintains stable ignition and complete combustion, thereby reducing unburned carbon while keeping the flame front attached to the nozzle
3Device complexity
If conventional flat-flame burner geometry is used, then the burner structure is simple, but the burner cannot achieve stable combustion of solid fuels
Solution Approach 1:
The burner divides the fuel and oxygen streams into multiple zones using segmented nozzles and annular passages, creating distinct regions for fuel introduction, oxygen mixing, and combustion that enable stable solid fuel combustion while maintaining relatively simple overall structure
Solution Approach 2:
The burner creates locally optimized conditions at the fuel nozzle with high-velocity oxygen jets and recirculation zones specifically positioned to enhance ignition and stabilize the flame front, while the rest of the burner maintains a simple conventional 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
The burner achieves a stable attached flame front, enhancing heat transfer and carbon burnout, and maintains flame stability, reducing unburned carbon and unsafe combustion conditions.
Implementation Method 1
the first guide vanes diverging from the major axis centerline in the flow direction by a first angle... thereby forming a central diffuser between the first guide vanes
Implementation Method 2
Divergence of the guide vanes in the diffuser lowers the velocity of a concentrated fraction of the solid fuel stream in a controlled manner
Implementation Method 3
an outer converging nozzle between each first guide vane and one of the long walls... The diluted fraction of the solid fuel stream flowing outside the guide vanes is accelerated in converging nozzles
Implementation Method 4
The diluted fraction of the solid fuel stream flowing outside the guide vanes is accelerated in converging nozzles on either side of the diffuser to a relatively high velocity
Implementation Method 5
The combination of relatively high velocity and low velocity streams flowing adjacent to one another creates a large flow recirculation pattern that substantially aids in sustaining stable combustion at the fuel nozzle tip
Implementation Method 6
The combination of relatively high velocity and low velocity streams flowing adjacent to one another creates a large flow recirculation pattern
Implementation Method 7
The primary oxygen may be accelerated over wedges that divert the primary oxygen away from the fuel stream, creating a recirculation zone adjacent the fuel stream
Implementation Method 8
The primary oxygen may be accelerated over wedges that divert the primary oxygen away from the fuel stream, creating a recirculation zone
Implementation Method 9
enhancing heat transfer and carbon burnout, and maintains flame stability, reducing unburned carbon
Data Source
AI summary
A wide-flame solid fuel/oxygen burner including a fuel nozzle having an aspect ratio of at least about 2 defined by the ratio of a fuel nozzle width, W, measured along a major axis centerline, to a fuel nozzle height, H, measured along a minor axis centerline, and long walls spaced substantially symmetrically from the major axis centerline, the fuel nozzle having an inlet width, WN; and a pair of guide vanes positioned on either side of the major axis centerline between that centerline and an adjacent long wall, the guide vanes diverging from the major axis centerline in the flow direction by an angle such that the guide vanes are closer together at an upstream end and farther apart at a downstream end, thereby forming a central diffuser between the guide vanes and an outer converging nozzle between each guide vane and one of the long walls.