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Title: Optical Fiber Sensor Instrumentation for Slagging Coal Gasifiers

Abstract

Coal gasifier is one of the most promising solutions for clean fossil energy. Refractory thickness monitoring and online real-time temperature measurement is needed for improved reliability and advanced process control for current and future generation power plants. The objective of this program is to design and implement an optical fiber based sensing system that could potentially be used to monitor refractory wall thickness and temperature inside a coal gasifier. For the thickness monitoring, the system should be able to operate at temperatures up to 1000 C. For this temperature range, silica fiber can still work so it is chosen for the sensor design. The measurement is based on a photon counting optical time domain reflectometer. A narrow light pulse is launched into a silica fiber which could be embedded into the gasifier refractory wall, and is partially reflected by the far end of the fiber. The time of flight of the light pulse in the fiber then gives an indication of the position of the fiber end, which is a function of the wall thickness when the fiber is embedded. Results obtained show a measurement accuracy of {+-}2cm in environment of 1000 C with a saw cut fiber end. Whenmore » the fiber end is corroded by sodium carbide at 900 C, the accuracy is {+-}3cm. For the temperature measurement, a single crystal sapphire fiber sensor is designed. The sapphire fiber guides the broadband light from a light emitting diode to a sapphire wafer functioning as a Fabry-Perot interferometer and the wafer optical thickness is a function of temperature. The returned optical signal is then demodulated by multimode fiber based whitelight interferometry. The system was tested up to 1500 C with a measurement accuracy of {+-}10 C for the entire measurement range.« less

Authors:
;
Publication Date:
Research Org.:
Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
943309
DOE Contract Number:  
FG26-05NT42532
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; ACCURACY; COAL; FABRY-PEROT INTERFEROMETER; FIBERS; INTERFEROMETRY; LIGHT EMITTING DIODES; MONITORING; MONITORS; MONOCRYSTALS; OPTICAL FIBERS; PHOTONS; POWER PLANTS; PROCESS CONTROL; RELIABILITY; SAPPHIRE; SILICA; SODIUM CARBIDES; TEMPERATURE MEASUREMENT; THICKNESS

Citation Formats

Wang, Anbo, and Cooper, Kristie. Optical Fiber Sensor Instrumentation for Slagging Coal Gasifiers. United States: N. p., 2008. Web. doi:10.2172/943309.
Wang, Anbo, & Cooper, Kristie. Optical Fiber Sensor Instrumentation for Slagging Coal Gasifiers. United States. https://doi.org/10.2172/943309
Wang, Anbo, and Cooper, Kristie. 2008. "Optical Fiber Sensor Instrumentation for Slagging Coal Gasifiers". United States. https://doi.org/10.2172/943309. https://www.osti.gov/servlets/purl/943309.
@article{osti_943309,
title = {Optical Fiber Sensor Instrumentation for Slagging Coal Gasifiers},
author = {Wang, Anbo and Cooper, Kristie},
abstractNote = {Coal gasifier is one of the most promising solutions for clean fossil energy. Refractory thickness monitoring and online real-time temperature measurement is needed for improved reliability and advanced process control for current and future generation power plants. The objective of this program is to design and implement an optical fiber based sensing system that could potentially be used to monitor refractory wall thickness and temperature inside a coal gasifier. For the thickness monitoring, the system should be able to operate at temperatures up to 1000 C. For this temperature range, silica fiber can still work so it is chosen for the sensor design. The measurement is based on a photon counting optical time domain reflectometer. A narrow light pulse is launched into a silica fiber which could be embedded into the gasifier refractory wall, and is partially reflected by the far end of the fiber. The time of flight of the light pulse in the fiber then gives an indication of the position of the fiber end, which is a function of the wall thickness when the fiber is embedded. Results obtained show a measurement accuracy of {+-}2cm in environment of 1000 C with a saw cut fiber end. When the fiber end is corroded by sodium carbide at 900 C, the accuracy is {+-}3cm. For the temperature measurement, a single crystal sapphire fiber sensor is designed. The sapphire fiber guides the broadband light from a light emitting diode to a sapphire wafer functioning as a Fabry-Perot interferometer and the wafer optical thickness is a function of temperature. The returned optical signal is then demodulated by multimode fiber based whitelight interferometry. The system was tested up to 1500 C with a measurement accuracy of {+-}10 C for the entire measurement range.},
doi = {10.2172/943309},
url = {https://www.osti.gov/biblio/943309}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Jul 19 00:00:00 EDT 2008},
month = {Sat Jul 19 00:00:00 EDT 2008}
}