Flame Amplifier High-Frequency Ionization for Fast Response
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Solution Overview
Problem
Existing flame monitoring systems in burners have a response time that varies with the level of the flame current, leading to potential false shutdowns due to their reliance on low-pass filters with large capacitors, which result in long response times and limited reaction to minor faults.
Innovation Solution
A flame amplifier with an ionization voltage generator producing an AC voltage above 60 Hz, allowing for a low-impedance low-pass filter design that quickly responds to flame failures, and evaluation electronics that sample the flame signal at a higher frequency, enabling rapid detection of flame extinguishment with minimal time delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large capacitors are used in the low-pass filter to maintain low output ripple at mains frequency, then the ripple is reduced, but the response time becomes unacceptably long
Solution Approach 1:
The patent changes the frequency parameter of the ionization voltage from mains frequency (50/60 Hz) to a higher frequency (e.g., 1 kHz or 10 kHz). This parameter change allows the low-pass filter to use much smaller capacitors while still achieving adequate ripple reduction, because the filter's time constant can be proportionally smaller at higher frequencies. Consequently, the response time is dramatically reduced without sacrificing ripple performance.
2Speed
If the low-pass filter is dimensioned for quick shutdown at maximum signal, then shutdown speed is improved, but false shutdowns occur at low signals due to electrical disturbances
Solution Approach 1:
The patent introduces a dynamic delay mechanism that adapts the shutdown detection timing based on the signal level. For low flame current signals, a longer delay period is applied before triggering shutdown, allowing transient disturbances to settle. For high signals, the delay is shorter, enabling faster response to actual flame failures. This dynamic adjustment resolves the contradiction between quick shutdown and false shutdown prevention.
3Reliability
If the response time is extended to filter out minor disturbances, then false shutdowns are reduced, but the system cannot meet maximum response time limits for actual flame failures
Solution Approach 1:
The system dynamically adjusts the delay period based on signal characteristics. When the flame current signal is strong and stable, the delay is minimized or eliminated, ensuring rapid detection of flame failures within regulatory time limits. When the signal is weak or fluctuating, a longer delay allows filtering of minor disturbances. This dynamic behavior simultaneously satisfies both reliability requirements and response time limits.
Solution Approach 2:
By changing the ionization voltage frequency to a higher value, the patent fundamentally alters the temporal characteristics of the system. The higher frequency creates more sampling points within any given time window, enabling the system to distinguish between transient disturbances (affecting only one or two cycles) and sustained flame failures (affecting many cycles). This parameter change allows the system to maintain short overall response time while using intelligent filtering to prevent false shutdowns.
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 system achieves a consistent response time and reduces false shutdowns by quickly detecting flame failures, allowing for reliable flame monitoring and combustion control with a high sampling rate and adjustable delay times.
Implementation Method 1
such devices, or flame intensifiers, often utilize the rectification effect of a flame to detect the presence or stage of combustion
Implementation Method 2
Most low-pass filters consist of a combination of an electrical capacitor and a series resistor
Implementation Method 3
During combustion, a direct current flows through the flame, which is measured by the flame intensifier and is referred to as the ionization current or flame current
Data Source
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AI summary
The invention relates to a flame amplifier for flame monitoring in a burner (1) comprising an ionization voltage generator (10) for generating an alternating voltage as the ionization voltage, an ionization electrode (2) for applying the ionization voltage to a flame generated by the burner (1), so that a direct voltage as the flame voltage is generated from the ionization voltage by the flame acting as a rectifier and a direct current flows as the flame current (3), and a flame signal conditioning system with a low-pass filter (5) at which an input voltage formed from the ionization voltage and the flame voltage, as well as a mixed current with an alternating current component and a direct current component corresponding to the flame current (3), are applied, wherein the ionization voltage generator (10) is configured to generate the ionization voltage at a frequency of more than 60 Hz.and wherein the low-pass filter (5) has a cutoff frequency corresponding to the frequency of the ionization voltage, such that the alternating current component of the mixed current is blocked and the low-pass filter (5) has a time constant corresponding to the frequency of the ionization voltage.