Dynamic Flame Detection Threshold for Air-Gas Burners
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Air-gas mixture burning appliances face challenges in reliably detecting flames at the burner surface, particularly distinguishing between normal flames and sustained flashback events, which can lead to overheating and unwanted noise due to fixed and independent flame detection thresholds.
Innovation Solution
The method involves adjusting the predetermined flame detection threshold for different operating points, such as ignition phase and normal operating range, based on parameters like firing rate and fan speed, to distinguish between normal and abnormal flame signals, ensuring reliable detection and preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed and independent flame detection threshold is used, then reliable flame detection can be achieved, but false indications occur during sustained flashback events and normal operation cannot be reliably distinguished
Solution Approach 1:
The flame detection threshold is changed from a fixed value to a dynamic value that varies with operating conditions. The control device adjusts the threshold based on time-variant functional variables including firing rate, air-gas ratio, and fan speed, allowing the system to adapt to different operational states and distinguish between normal flames and flashback events
Solution Approach 2:
The detection threshold parameter is made variable by linking it to operating parameters such as firing rate, air-gas ratio, and fan speed. By changing the threshold parameter dynamically according to these operating conditions, the system can accurately detect flames across different operating points while avoiding false indications during flashback events
2Measurement precision
If the flame detection threshold is set significantly smaller to detect normal flames, then normal flame detection is reliable, but overheating occurs during flashback events due to inability to distinguish abnormal conditions
Solution Approach 1:
The detection threshold is dynamically adjusted based on operating parameters. During normal operation, the threshold is set lower to detect small flames accurately. During flashback conditions, the threshold is raised to prevent false detection, thereby avoiding overheating while maintaining normal detection capability
Solution Approach 2:
The system uses feedback from operating parameters (firing rate, air-gas ratio, fan speed) to continuously adjust the detection threshold. This feedback mechanism allows the system to adapt the threshold to current operating conditions, preventing overheating during flashback while maintaining sensitivity during normal operation
3Object-affected harmful factors
If the flame detection threshold is set significantly larger to avoid false detection during flashback, then overheating is prevented, but normal flame detection becomes unreliable
Solution Approach 1:
The threshold dynamically adapts to operating conditions rather than being fixed at a high value. During normal operation, the threshold is lowered to ensure reliable detection. During flashback events, the threshold is raised to prevent false detection and overheating, thus maintaining reliability across different operational states
4Device complexity
If a fixed flame detection threshold is used independent of operating conditions, then device complexity is low, but the system cannot adapt to different operating points and firing rates
Solution Approach 1:
The control device performs multiple functions: it controls the air-gas mixing unit, burning unit, and flame detector, and additionally dynamically adjusts the detection threshold based on operating conditions. This multi-functionality allows a single device to handle both operation control and adaptive detection, reducing overall system complexity while improving adaptability
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 adjustment allows for improved flame detection at the burner surface, preventing false indications and overheating by tailoring the detection threshold to varying operating conditions, ensuring secure and reliable operation.
Implementation Method 1
a flame detector for sensing presence of a flame at the burner surface on the basis of a predetermined flame detection threshold
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
In an air-gas mixture burning appliance (100) that comprises an air-gas mixing unit (110) for mixing of air and gas to form a combustible air-gas mixture (130), a burning unit (120) with a burner surface (124) that is arranged downstream of the air-gas mixing unit (110) for burning the combustible air-gas mixture (130) at the burner surface (124), and a flame detector (150) for sensing presence of a flame (122) at the burner surface (124) on the basis of a predetermined flame detection threshold, the predetermined flame detection threshold is adjustable to vary for at least two different operating points of the air-gas mixture burning appliance (100).