Burner Control Facility Ionization Drift Correction
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Solution Overview
Problem
Existing burner system control facilities face challenges in accurately correcting drift in ionization current due to factors like accretions and bending of the ionization electrode, leading to inaccuracies in combustion control and potential pollutant emissions.
Innovation Solution
A control facility for a burner system that adjusts the air coefficient above the stoichiometric value of λ=1, using precise modeling and targeted changes in the air coefficient to calculate a target value, thereby minimizing temperature impulses and contamination, and regularly repeating the test to account for creeping drift phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the air coefficient is adjusted above the stoichiometric value of λ=1 for calibration purposes, then the ionization signal can be captured and target value can be calculated, but temperature impulses and contamination of the burner and ionization electrode increase
Solution Approach 1:
The system performs preliminary calibration actions by temporarily adjusting the air coefficient above stoichiometric values to capture ionization signals and calculate target values. This preliminary calibration enables subsequent accurate control operations without requiring continuous excessive air coefficient adjustments, thus reducing cumulative temperature impulses and contamination while maintaining measurement precision.
2Device complexity
If the actuating member characteristic must be precisely reproducible and located in a narrow tolerance range, then the control system can be simplified, but the system becomes more sensitive to manufacturing variations and drift
Solution Approach 1:
The system implements feedback mechanisms that continuously monitor ionization signals and adjust control parameters accordingly. This feedback loop compensates for manufacturing variations and drift in actuating member characteristics, allowing the system to maintain reliability without requiring extremely tight tolerance ranges or complex calibration procedures for each individual component.
Solution Approach 2:
The system dynamically changes control parameters such as the air coefficient based on real-time ionization signal measurements. By adjusting parameters adaptively rather than relying on fixed, precisely reproducible actuating member characteristics, the system maintains reliability under varying operating conditions and drift while keeping the control system relatively simple.
3Productivity
If the ionization electrode is exposed to the flame zone continuously, then the sensor can continuously monitor combustion quality, but accretions and bending of the electrode occur leading to signal drift
Solution Approach 1:
The system performs periodic calibration operations where the air coefficient is temporarily adjusted above stoichiometric values to capture fresh ionization signals. These periodic calibration actions help reset and re-reference the measurement system, compensating for gradual drift caused by continuous exposure to the flame zone and accretions on the electrode, thereby maintaining measurement precision while allowing continuous monitoring.
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 allows for reliable correction of the ionization signal target value, maintaining accuracy and reducing pollutant emissions, with the air coefficient being adjusted to λ>1.05 and reduced by Δλ<−0.06, ensuring high precision and low noise in ionization signal measurements, even with significant drift, and maintaining the lower limit of the air coefficient range.
Implementation Method 1
When an AC voltage is applied, an ionization current flows through the electrode and the flame
Implementation Method 2
The control facility contains at least a flame amplifier at the ionization electrode to generate an ionization signal
Data Source
AI summary
A control facility is provided for a burner system having a burner, actuators with which the supply of fuel and air to the burner is set, and an ionization electrode arranged in the flame zone. The control facility is equipped with a flame amplifier at the ionization electrode to generate an ionization signal and a positioning facility which, in control operation, positions a first actuator and regulates a second actuator by using a corresponding target value for the ionization signal. The positioning facility carries out a control operation in a first test step, it shifts the actuators toward a supply ratio corresponding to an air coefficient above the stoichiometric value of λ=1 and in so doing captures the ionization signal in a second test step, and it calculates a target value from this and from stored data in a third test step. Correction of drift therefore takes place.