SiC Flame Detectors Discriminate Premixed and Diffusion Flames
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Solution Overview
Problem
Current flame detection systems in gas turbines cannot discriminate between different types of flames, leading to potential damage and catastrophic malfunctions during flame holding or flashback events in combustors.
Innovation Solution
The implementation of optical flame detection using SiC solid-state flame detectors that differentiate between premixed and diffusion flames by detecting specific ultraviolet and thermal emissions, allowing for precise identification and action to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ion-sensing detectors or thermocouples are used to detect flame presence, then flame detection capability is provided, but the system cannot discriminate between different flame types (premixed vs diffusion)
Solution Approach 1:
The detection system is segmented into multiple independent optical detectors, each sensitive to different wavelength ranges. One detector monitors ultraviolet emissions (indicative of premixed flame), while another monitors visible/thermal emissions (indicative of diffusion flame). This segmentation allows simultaneous detection of different flame types without requiring a single complex multi-functional detector.
Solution Approach 2:
The system transitions from single-parameter detection (simple flame presence) to multi-dimensional detection by adding wavelength discrimination capability. By measuring emissions across different spectral dimensions (ultraviolet vs visible ranges), the system achieves flame type discrimination while maintaining relatively simple individual detector designs.
2Reliability
If flame holding or flashback occurs in the premixing zone, then combustion efficiency may be maintained, but serious damage occurs to the combustor and system malfunction ensues
Solution Approach 1:
The optical detection system performs preliminary monitoring of flame characteristics before damage occurs. By continuously detecting the spectral emissions from the combustion zone, the system can identify the onset of flashback or flame holding conditions and trigger protective actions (such as shutting down fuel flow) before serious damage to the combustor occurs.
Solution Approach 2:
The system establishes a feedback loop where optical detectors continuously monitor flame type, the control system compares detected emissions against expected patterns, and corrective actions are automatically implemented when abnormal conditions are detected. This closed-loop feedback enables real-time protection against combustor damage from flashback events.
3Loss of time
If simple flame detection is used, then device complexity is minimized, but the system cannot provide timely discrimination to prevent damage during flashback events
Solution Approach 1:
The optical detection system operates continuously, with detectors constantly monitoring combustion zone emissions. This continuous monitoring eliminates detection delays and enables immediate identification of flame type changes. The system maintains uninterrupted observation of combustion characteristics, allowing rapid response to flashback conditions without requiring complex sequential sensing operations.
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 solution effectively discriminates between flame types, enabling timely intervention to prevent damage to the gas turbine by reducing or eliminating fuel flow during flashback events, thus maintaining optimal operating conditions and reducing emissions.
Implementation Method 1
The SiC solid state flame detector has a responsivity envelope that includes emission sensitivity to wavelengths between about 200 nm and 430 nm. The most intense emission at about 300 nm is produced by the excited OH molecule which is a direct product of the combustion process.
Implementation Method 2
The SiC photodiodes responsivity characteristics it is not very sensitive to combustor hot wall blackbody radiation or 350 to 450 nm radiation from soot.
Data Source
AI summary
Optical flame holding and flashback detection systems and methods are provided. Exemplary embodiments include a combustor including a combustor housing defining a combustion chamber having combustion zones, flame detectors disposed on the combustor housing and in optical communication with the combustion chamber, wherein each of the flame detectors is configured to detect an optical property related to one or more of the combustion zones.