Burner Airflow Modifier Turbulence for Asphalt Dryer Combustion
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Solution Overview
Problem
Asphalt dryer plants face inefficiencies in combustion due to short combustion zones and interference from falling aggregates and airborne dust, leading to incomplete combustion and high excess air usage, resulting in increased energy consumption and pollutant emissions.
Innovation Solution
A burner system with airflow modifier devices that create turbulence to enhance fuel-air mixing, allowing for more precise control of excess air and improved combustion efficiency, including a fuel-atomising burner nozzle and adjustable airflow channels to optimize combustion conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excess air is introduced into the burner to prevent incomplete combustion, then combustion completeness is improved, but heat transfer efficiency deteriorates due to inefficient energy utilization
Solution Approach 1:
The invention changes the physical parameters of air flow by introducing turbulence through deflectors and swirl devices. This transforms the air flow from laminar to turbulent, enhancing mixing between fuel and air without increasing the total air volume. The turbulence parameter (Reynolds number) is increased locally to improve combustion completeness while maintaining overall air quantity at stoichiometric or slightly excess levels, thus resolving the contradiction between combustion completeness and heat transfer efficiency.
Solution Approach 2:
The invention applies local quality changes by creating zones of high turbulence and mixing within the combustion chamber through strategically placed deflectors and swirl devices. These local modifications enhance fuel-air mixing in critical zones without affecting the overall air flow rate. This allows complete combustion to be achieved in specific regions while maintaining efficient heat transfer in other zones, resolving the contradiction between combustion completeness and energy utilization.
2Length of stationary object
If a short combustion zone is used in the dryer, then the dryer length is reduced, but combustion efficiency deteriorates due to insufficient residence time
Solution Approach 1:
The invention introduces periodic or oscillating air flow patterns through the use of deflectors that create alternating zones of high and low velocity. This periodic action enhances mixing and maintains turbulent conditions throughout the short combustion zone, allowing sufficient combustion reactions to occur within the reduced space. The oscillating flow patterns ensure that fuel and air continuously mix and react, maintaining combustion efficiency despite the shorter residence time.
Solution Approach 2:
The invention employs mechanical vibration in the form of turbulent eddies and vortex structures created by swirl devices and deflectors. These vibrational flow patterns enhance the mixing rate and reaction rate within the combustion zone. The turbulent mixing increases the effective contact between fuel and oxidizer, compensating for the reduced residence time in the shorter dryer, thus maintaining combustion efficiency while reducing overall length.
3Quantity of substance
If aggregates and dust interfere with the combustion zone, then mixing is enhanced, but incomplete combustion increases due to disrupted flame stability
Solution Approach 1:
The invention introduces air deflectors and swirl devices as intermediary elements that mediate between the incoming air flow and the combustion zone. These intermediaries organize the chaotic flow patterns caused by aggregates and dust, creating structured turbulent zones that enhance mixing while protecting the flame core. The deflectors act as intermediaries that channel and organize the flow, ensuring that fuel-air mixing is enhanced without compromising flame stability.
Solution Approach 2:
The invention converts the harmful effect of turbulent flow disruption caused by aggregates and dust into a beneficial mixing mechanism. By strategically placing deflectors and swirl devices, the invention harnesses the chaotic flow patterns and transforms them into controlled turbulence that enhances fuel-air mixing. The previously harmful flow disruption is converted into useful mixing action, improving combustion efficiency while maintaining flame stability through proper device design and positioning.
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 system achieves more complete combustion, reducing emissions of pollutants like carbon monoxide and improving energy efficiency by minimizing excess air usage, leading to lower energy consumption and extended bag filter life.
Implementation Method 1
a first airflow modifier device mounted in or across the opening at the upstream end of the combustion chamber such that there is a gap constituting an air escape channel around a periphery of the first airflow modifier device, the first airflow modifier device having one or more windows therein through which a flow of air provided by the fan is directed into the combustion chamber to mix with atomised fuel from the burner nozzle, the one or more windows being configured to impart turbulence to the airflow
Implementation Method 2
a burner chamber in which is mounted a fuel-atomising burner nozzle and means for conveying fuel to the burner nozzle; the burner nozzle being arranged to direct a flow of atomised fuel into the combustion chamber
Implementation Method 3
a combustion chamber in which the fuel is burnt; the combustion chamber having an opening at an upstream end communicating with the burner chamber and an opening at a downstream end thereof for passing combustion gases and heated air into a drying chamber of the dryer
Data Source
AI summary
The invention provides a burner configured for use with a dryer for drying aggregates, the burner comprising:a burner chamber (3) is which is mounted a fuel-atomizing burner nozzle (3.32) and means for conveying fuel to the burner nozzle;means providing a flow of air through the burner chamber and into the combustion chamber;a combustion chamber (4) in which the fuel is burnt; the combustion chamber (4) having an opening at an upstream end thereof communicating with the burner chamber (3) and an opening at a downstream end thereof for passing combustion gases and heated air into a drying chamber of the dryer; the burner nozzle (3.32) being arranged to direct a flow of atomized fuel into the combustion chamber;a first airflow modifier device (3.11) mounted in or across the opening at the upstream end of the combustion chamber such that there is a gap constituting an air escape channel around a periphery of the first airflow modifier device,the first airflow modifier device (4.3) having one or more windows therein through which a flow of air provided by the fan is directed into the combustion chamber to mix with atomized fuel from the burner nozzle, the one or more windows being configured to impart turbulence to the airflow; anda second airflow modifier device (4.3) comprising one or more air deflector elements (4.31) mounted peripherally about the opening at the upstream end of the combustion chamber, the second airflow modifier device (4.3) being arranged to impart turbulence to excess air passing through the said air escape channel.