Flame Rectification Sensor for Fouling-Resistant Burner Detection
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Solution Overview
Problem
Flame rods used for detecting burner flames suffer from fouling due to soot and deposits, leading to reduced sensitivity and the need for frequent replacement, which complicates reliable flame detection.
Innovation Solution
A burner flame detection system utilizing a conductive flame sensor and a flame sensing circuit that supplies an alternating current with a frequency of 24 kHz to 300 kHz, allowing for effective detection of a flame even with accumulated deposits, and optionally incorporating a hot surface igniter with a conductive pattern for simultaneous heating and sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flame rod is used for flame detection, then flame presence can be detected, but the flame rod becomes fouled by soot and deposits leading to reduced sensitivity and requiring frequent replacement
Solution Approach 1:
The patent changes the electrical parameters by using high-frequency alternating current (24 kHz to 300 kHz) instead of direct current or low-frequency AC. This parameter change allows the system to maintain detection sensitivity despite fouling, as the high-frequency signal can penetrate through soot and deposits more effectively, resolving the contradiction between reliable operation and maintaining measurement precision over time
2Reliability
If a flame rod is used for flame detection, then flame presence can be detected, but frequent replacement is required due to fouling, increasing maintenance complexity
Solution Approach 1:
The system enables the flame sensor to effectively self-clean by using high-frequency AC that prevents soot and deposits from accumulating to problematic levels. The high-frequency electrical signal keeps the flame rod surface cleaner for longer periods, reducing maintenance frequency and complexity while maintaining reliable detection
Solution Approach 2:
By changing to high-frequency AC operation, the system extends the operational life of the flame rod between maintenance intervals, thereby reducing the complexity and frequency of replacements without compromising detection reliability
3Duration of action of stationary object
If high-frequency AC is used to reduce fouling impact, then component lifespan is extended, but energy consumption increases
Solution Approach 1:
The system applies high-frequency AC only during the flame detection phase, not continuously. The controller activates the high-frequency signal only when flame presence needs to be determined, thereby extending component lifespan through periodic cleaning action while minimizing overall energy consumption by avoiding continuous high-frequency operation
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 provides a stable binary signal for flame presence detection, reducing the impact of fouling and extending the lifespan of the detection components by using high-frequency AC to maintain sensitivity and allowing for continuous operation without frequent maintenance.
Implementation Method 1
When the burner is in an ignited state and the alternating current is supplied to the conductive terminal, the flame sensing circuit generates a rectified current from the conductive flame sensor conductive terminal to the burner
Data Source
AI summary
Systems and methods for detecting the presence of a burner flame using flame rectification are shown and described. A conductive flame sensor is positioned to conduct electricity to a burner flame when the burner is lit. The flame provides a conductive path to the burner conductive body and when operatively connected to an alternating current source, half-wave rectifies the current flowing to the sensor. A flame sensing circuit provides an output signal that is conditioned for use as an input to a flame indicator and/or a controller that is configured to shut off gas flow to the burner when no flame is present after an attempt at igniting the burner.