Multi-fuel burner oxygen injection for complete combustion
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Solution Overview
Problem
Multi-fuel burners face challenges in efficiently burning low-calorific fuels due to poor burnout behavior and uneven temperature distribution, leading to reduced clinker quality and increased risk of malfunctions, particularly when using solid fuels with varying grain sizes and moisture levels, which results in incomplete combustion and potential ignition issues within the fuel feed lines.
Innovation Solution
A multi-fuel burner design featuring a perforated wall section in the secondary fuel feed with numerous gas outlet openings connected to an oxygen feed line, ensuring gentle introduction of oxygen-rich gas into the secondary fuel flow, promoting turbulent mixing and reducing the risk of local oxygen excess concentrations, along with a double-walled pipe design and inert gas introduction to manage potential ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the amount of transport air for substitute fuel is increased to improve flight properties, then the fuel is carried too quickly out of the hot area close to the burner, but this also causes increased wear and undesirable cooling effect
Solution Approach 1:
Oxygen is introduced into the secondary fuel flow before the fuel exits the burner, pre-enriching the fuel stream with oxygen. This preliminary oxygenation ensures sufficient combustion support without requiring excessive transport air, thereby maintaining fuel residence time in the hot zone while still achieving complete combustion
Solution Approach 2:
Oxygen enrichment is applied locally at the burner outlet where the secondary fuel is discharged, rather than increasing transport air throughout the entire system. This localized intervention provides combustion support exactly where needed without affecting the overall transport air quantity and associated cooling effects
2Reliability
If concentrated oxygen entry into secondary fuel feed is used to promote combustion, then oxygen and fuel mix in the feed line, but this leads to overconcentration of oxygen downstream and formation of zones at risk of ignition
Solution Approach 1:
Instead of a single concentrated oxygen entry point, the system uses multiple distributed oxygen injection points along the secondary fuel feed line. This segmentation distributes the oxygen enrichment process along the fuel stream, preventing localized overconcentration while ensuring gradual and uniform mixing
Solution Approach 2:
The secondary fuel feed line itself serves as an intermediary mixing chamber where oxygen is gradually introduced and mixed with the fuel stream before discharge. This intermediate mixing zone allows controlled oxygen-fuel interaction without creating dangerous concentration gradients
3Productivity
If high speeds in substitute fuel ducts are used to improve fuel conveyance, then fuel transport is enhanced, but this causes increased wear and undesirable cooling effect
Solution Approach 1:
The oxygen enrichment function is extracted from the transport air stream and applied separately through dedicated oxygen injection points. This separation allows the transport air to maintain optimal velocity for fuel conveyance without the additional burden of carrying oxygen, reducing wear and cooling effects while still achieving complete combustion through the added oxygen
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 design enhances the reliability of the burner by ensuring uniform mixing of oxygen and fuel, reducing the risk of malfunctions, and allowing for increased use of low-calorific fuels, thereby improving clinker quality and operational efficiency while minimizing the risk of ignition and clogging.
Implementation Method 1
promoting turbulent mixing and reducing the risk of local oxygen excess concentrations
Implementation Method 2
ensuring sufficient burnout of the secondary fuel and homogeneous temperature distribution in the furnace chamber
Data Source
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AI summary
The invention relates to a multi-fuel burner in which a feed for a primary fuel, a feed for a primary oxidizer, and at least one secondary fuel feed open into a furnace chamber. To promote the complete and rapid combustion of the secondary fuel, the invention provides that an oxygen-rich gas is introduced into the secondary fuel via a gas distributor, which is connected to a wall section of the secondary fuel feed having a plurality of gas outlet openings. This wall section is preferably located in the upper half of the secondary fuel feed.The uniform introduction of the oxygen-rich gas well before the outlet of the multi-fuel burner into the furnace chamber enables a good and uniform mixing of the secondary fuel with the oxygen-rich gas, which significantly accelerates the subsequent combustion of the secondary fuel in the furnace chamber.