Actively Cooled Flame Temperature Measurement for Gas Burners
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Solution Overview
Problem
Existing gas burner systems struggle to meet the 1-second fuel valve closure time requirement after flame extinction, as the thermocouple cooling period is too long, making them unsuitable for automatic burners in domestic and industrial applications.
Innovation Solution
A method for monitoring gas burner system operations using an actively cooled flame temperature measurement installation, which rapidly cools after flame extinction, allowing for immediate fuel supply interruption, and also determines the air-fuel ratio to ensure safe and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermocouple is used to monitor flame temperature, then the system is simple to implement and robust, but the response time is too long (up to 30 seconds) to meet the 1-second closure requirement
Solution Approach 1:
The thermocouple is pre-cooled by cooling air flowing through the protective sheath before flame detection. This preliminary cooling ensures that when the flame is extinguished, the thermocouple can rapidly detect the temperature drop and trigger fuel valve closure within the required 1-second timeframe, eliminating the 30-second delay of conventional systems.
2Reliability
If the thermocouple remains hot after flame extinction, then the thermoelectric voltage remains sufficient to keep the fuel valve open, but this causes delayed fuel valve closure and safety issues
Solution Approach 1:
A cooling air flow is introduced as an intermediary element that passes through the protective sheath surrounding the thermocouple. This cooling air actively removes heat from the thermocouple, ensuring rapid temperature drop detection upon flame extinction. The cooling air acts as a mediator between the flame environment and the thermocouple, enabling safe and timely fuel valve closure.
3Object-generated harmful factors
If hydrogen or hydrogen/natural gas mixture is used as fuel to reduce CO2 emissions, then environmental performance improves, but the air-fuel ratio and operating parameters change requiring precise monitoring
Solution Approach 1:
The actively cooled thermocouple provides real-time feedback on flame temperature and air-fuel ratio conditions. By monitoring the thermoelectric voltage generated under controlled cooling conditions, the system detects changes in combustion characteristics when using hydrogen or hydrogen/natural gas mixtures. This feedback enables precise adjustment of operating parameters to maintain optimal air-fuel ratio and safe combustion despite the different fuel properties.
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 actively cooled flame temperature measurement installation significantly shortens the response time between flame extinction and fuel valve closure, enabling compliance with stringent safety standards and ensuring safe and reliable operation of gas burner systems.
Implementation Method 1
An electric voltage which is generated by the flame temperature by virtue of the thermoelectric effect (Seebeck effect) in the case of an active flame
Implementation Method 2
The actively cooled flame temperature measurement installation that is permanently cooled by cooling air as a result of a forced convection
Data Source
AI summary
A method for monitoring an operation of a gas burner system in which a fuel/air mixture is ignited and a flame is generated by a burner during operation, includes: measuring the temperature of the flame by a flame temperature measurement installation that is actively cooled by impingement with cooling air; evaluating the temperature of the flame by an evaluation installation; interrupting a fuel supply to the burner in response to the temperature of the flame dropping below a critical value or having a specific negative gradient; determining an air-fuel ratio from the temperature of the flame; and interrupting the fuel supply to the burner in the event of an anomaly in the air-fuel ratio.