Burner Air Ratio Control via Ionization and Flame Temperature
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Solution Overview
Problem
Existing methods for regulating the air ratio in burners, such as those using ionization current measurements, face challenges due to thermal coupling changes over time, leading to inaccurate air ratio control and increased pollutant emissions, especially when operating at stoichiometric conditions.
Innovation Solution
A method that utilizes both ionization current and flame temperature measurements to calibrate and control the air ratio, allowing for accurate air ratio determination and reducing pollutant emissions by using a two-channel system with ionization current for quick response and flame temperature for precise adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If ionization current measurement is used for air ratio control, then quick response is achieved, but measurement precision deteriorates due to thermal coupling changes
Solution Approach 1:
The patent introduces flame temperature as an intermediary measurement parameter that indirectly reflects air ratio conditions. Instead of relying directly on ionization current which is affected by thermal coupling changes, the system uses flame temperature (measured via thermocouple or radiation) as a more stable intermediary indicator of combustion conditions, thereby improving measurement precision while maintaining the speed benefits of electronic sensing.
Solution Approach 2:
The patent replaces the mechanical/thermal coupling-based ionization electrode system with an optical/radiation-based measurement system for flame temperature detection. This substitution eliminates the thermal coupling problem between the electrode and burner, as the new system measures temperature through radiation or remote sensing without direct thermal contact, thereby improving measurement stability and precision.
2Measurement precision
If calibration at lambda=1 is performed, then proportionality factor determination is achieved, but pollutant emissions increase significantly
Solution Approach 1:
The patent performs calibration actions during burner startup or maintenance periods when the burner is not in active service, rather than during normal operation. This preliminary calibration approach allows for accurate proportionality factor determination without compromising normal combustion efficiency, as calibration occurs when heating demand is minimal or the system is already being shut down.
Solution Approach 2:
The patent creates a theoretical or simulated calibration model that can determine the proportionality factor without physically operating the burner at lambda=1 conditions. By using computational models, historical data, or alternative measurement methods that copy the calibration process virtually, the system achieves accurate calibration while avoiding the harmful emissions associated with actual stoichiometric combustion operations.
3Device complexity
If single-channel ionization current control is used, then device complexity is reduced, but reliability deteriorates due to thermal coupling changes
Solution Approach 1:
The patent merges multiple measurement approaches (ionization current sensing with flame temperature detection) into a unified control system. By combining these complementary measurement methods, the system achieves improved reliability through cross-validation and redundancy, while the integrated design minimizes the increase in overall device complexity through shared control electronics and coordinated processing.
Solution Approach 2:
The patent implements a feedback mechanism where flame temperature measurements continuously monitor combustion conditions and provide corrective information to adjust the air ratio control. This feedback loop compensates for drift in ionization current readings caused by thermal coupling changes, thereby maintaining reliable air ratio control without requiring complex periodic calibration routines or multiple independent control systems.
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 approach provides reliable and precise air ratio control, reducing pollutant emissions and improving combustion efficiency by combining the fast response of ionization current measurements with the accuracy of flame temperature measurements, enabling operation within the optimal air ratio range.
Implementation Method 1
the air ratio is detected by measuring an ionization current flowing from an ionization electrode placed in the combustion chamber
Implementation Method 2
an alternating voltage is applied to the ionization electrode and a current flowing from the ionization electrode, which is rectified due to the rectifier property of the flame
Implementation Method 3
the fuel is burned with excess air
Data Source
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AI summary
The method involves disconnecting an ignition electrode (102) by a medium for generating the ignition voltage (104). An electrical signal (115a) is sensed to an ionization electrode (103) and the signal is derived dependent on an air ratio in response to the electrical signal. Another electrical signal (115b) is sensed to the ignition electrode and another signal dependent on the air ratio is derived in response to the latter electrical signal. An independent claim is included for a burner, particularly oil or gas burner with an ignition electrode.