Ionization Electrode Regeneration via High-Frequency Plasma Heating
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Solution Overview
Problem
Ionization electrodes in burners, especially those with aluminum content, face challenges in providing reliable measurements over long periods and during cold start phases due to the formation of an aluminum oxide layer, which is electrically and thermally insulating, leading to weakened or suppressed measurement signals.
Innovation Solution
Applying a second AC voltage with a higher frequency for a definable time interval after the burner has started, specifically between 10 to 100 MHz, to regenerate the ionization electrode by heating the plasma and reducing the oxide layer thickness, thereby ensuring reliable measurements during cold starts and long-term operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ionization electrode with aluminum content is used in a burner, then the electrode provides good initial measurement signal, but over time an aluminum oxide layer forms that is electrically and thermally insulating, weakening or suppressing the measurement signal
Solution Approach 1:
The patent applies periodic high-frequency voltage pulses (e.g., at 13.56 MHz) to the ionization electrode at defined intervals during operation. This periodic action removes the insulating aluminum oxide layer that forms over time, restoring the electrode's electrical conductivity and measurement capability without requiring replacement, thus resolving the contradiction between initial reliability and long-term service life
Solution Approach 2:
The patent changes the electrical parameter (voltage frequency) from standard operating frequency to high frequency (e.g., 13.56 MHz) during regeneration cycles. This parameter change enables the removal of the oxide layer through dielectric heating and ion bombardment effects, restoring the electrode's electrical properties and extending its functional life while maintaining measurement reliability
2Reliability
If a high-frequency AC voltage is applied to regenerate the ionization electrode, then the oxide layer is reduced and measurement signal is restored, but the burner control must be interrupted during the regeneration process
Solution Approach 1:
The patent applies partial action by using brief, targeted high-frequency voltage pulses rather than continuous high-frequency treatment. The regeneration is performed in short intervals (e.g., a few seconds) at defined periods during burner operation, sufficient to remove the oxide layer while minimizing interruption to the burner control process and maintaining overall productivity
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 method enables reliable ionization measurements by reversing the aging process of the electrode, ensuring fault-free regulation and control of the burner, even during cold starts, by accelerating the heating process and maintaining optimal combustion control.
Implementation Method 1
the second frequency and the second alternating current voltage are selected to be so high that during operation the plasma in the vicinity of the ionization electrode is heated to an excess temperature
Implementation Method 2
Applying a second AC voltage with a higher frequency for a definable time interval after the burner has started, specifically between 10 to 100 MHz, to regenerate the ionization electrode by heating the plasma
Implementation Method 3
Cracks in the aluminum oxide layer often form later due to alternating thermal loads, which can even lead to partial areas of the aluminum oxide flaking off
Data Source
Figure 1
AI summary
The invention relates to a method for regenerating an ionization electrode (3) for measuring the ionization in a flame area (2) of a burner (1), wherein, when the burner (1) is started, the ionization electrode (3) is subjected to a second alternating voltage with a second frequency for a predefinable time interval (Δt), which is higher than a first frequency of a first alternating voltage used for continuous operation.The invention also relates to a device, in particular for carrying out the above method, comprising an ionization electrode (3) arranged in a burner (1) such that it can measure an ionization current in a flame area (2) during operation of the burner (1), a first alternating current source (5) for a first alternating current with a first frequency, a second alternating current source (6) for a second alternating current with a second, higher frequency, and a switching device (7) which switches on the second alternating current source (6) during operation according to predefinable criteria. The present invention avoids malfunctions during cold starts of a burner due to measurement errors in the ionization current, even during long-term operation, and enables regeneration of the ionization electrode and ensures trouble-free control through accelerated heating during a cold start.