Fiber Optic Flame Sensor for Combustor Monitoring
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Solution Overview
Problem
Current methods for monitoring flame properties in high pressure combustors and gasifiers are limited by the need for intrusive temperature probes and are prone to measurement distortion due to harsh environments and particulate matter, providing insufficient spatially-resolved information for optimizing combustion processes.
Innovation Solution
A non-intrusive imaging monitoring sensor using an imaging fiber optic bundle coupled with a spectroscopic imaging system and a pinhole-sized observation port, which collects and analyzes light from within the combustor or gasifier to provide spectrally-resolved light intensities, minimizing the impact of purging gas and avoiding the need for lenses or other optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intrusive temperature probes are used to measure flame properties, then temperature measurements can be obtained, but the probes are obscured by particulate matter and provide only point or line-of-sight information
Solution Approach 1:
The probe is divided into multiple optical fibers arranged in an array, with each fiber collecting light from a specific location in the flame. This segmentation allows simultaneous measurement of multiple spatial points, providing full spatially-resolved temperature distribution across the flame cross-section rather than a single point measurement.
Solution Approach 2:
The system creates an optical copy of the flame's spatial structure by transmitting light through the fiber optic array to a detector system. This optical copying preserves the spatial information of the flame while allowing non-contact measurement, avoiding the obscuration problem of physical probes.
2Reliability
If optical pyrometers are used to measure flame temperature, then non-contact measurement is achieved, but only limited spatial information is provided and measurements may be distorted by the harsh environment
Solution Approach 1:
The optical pyrometer is segmented into multiple discrete optical fibers, each independently measuring temperature at its specific location. This allows the system to reconstruct the complete spatial temperature distribution while maintaining non-contact measurement reliability in the harsh combustion environment.
Solution Approach 2:
The fiber optic array acts as an intermediary between the flame and the detection system. The fibers transmit optical information from the flame to external detectors without requiring direct line-of-sight through the harsh environment, protecting the measurement system from obscuration while maintaining spatial resolution.
3Loss of information
If fiber optic arrays are used to collect light from the flame, then spatially-resolved information is obtained, but the system complexity increases
Solution Approach 1:
Multiple optical fibers are merged into a single integrated probe assembly that functions as one cohesive measurement unit. The fiber array is combined with a common housing and detection system, simplifying the overall structure while maintaining the ability to collect spatially-resolved information from multiple locations simultaneously.
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
Enables real-time, spatially-resolved monitoring of flame properties, providing accurate data on temperature, oxygen/coal ratios, steam/coal ratios, and sulfur oxide emissions, improving the characterization and optimization of combustor or gasifier performance while withstanding harsh conditions.
Implementation Method 1
an imaging fiber optic bundle coupled with a spectroscopic imaging system
Implementation Method 2
spectroscopic imaging system employing an imaging monochromator and intensified CCD camera
Implementation Method 3
Use of the pinhole-sized observation port or opening provides a means for focusing the flame light onto the fiber optic bundle entrance
Implementation Method 4
The temperature measuring instrument is provided with cooling means for cooling at least the portion of the slag shield extending into the interior of the gasifier and is provided with purge gas means for supplying a flow of purge gas in the area around the temperature measuring instrument to purge particulate matter therefrom
Data Source
AI summary
A system for real-time monitoring of flame properties in combustors and gasifiers which includes an imaging fiber optic bundle having a light receiving end and a light output end and a spectroscopic imaging system operably connected with the light output end of the imaging fiber optic bundle. Focusing of the light received by the light receiving end of the imaging fiber optic bundle by a wall disposed between the light receiving end of the fiber optic bundle and a light source, which wall forms a pinhole opening aligned with the light receiving end.