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Title: Transpiration-purged optical probe: a novel sensor for high temperature harsh environments

Abstract

Typical control systems that are found in modern power plants must control the many physical aspects of the complex processes that occur inside the various components of the power plant. As detection and monitoring of pollutants becomes increasingly important to plant operation, these control systems will become increasingly complex, and will depend upon accurate monitoring of the concentration levels of the various chemical species that are found in the gas streams. In many cases this monitoring can be done optically. Optical access can also be used to measure thermal emissions and the particulate loading levels in the fluid streams. Some typical environments were optical access is needed are combustion chambers, reactor vessels, the gas and solid flows in fluidized beds, hot gas filters and heat exchangers. These applications all have harsh environments that are at high temperatures and pressures. They are often laden with products of combustion and other fine particulate matter which is destructive to any optical window that could be used to monitor the processes in these environments in order to apply some control scheme over the process. The dust and char that normally collects on the optical surfaces reduces the optical quality and thus impairs the abilitymore » of the optical surface to transmit data. Once this has occurred, there is generally no way to clean the optical surface during operation. The probe must be dismounted from the vessel, disassembled and cleaned or replaced, then remounted. This would require the shutdown of the particular component of the plant where optical monitoring is required. This renders the probe ineffective to be used as the monitoring part of any control system application. The components of optical monitoring equipment are usually built in supporting structures that require precise alignment. This is almost always accomplished using fine scale adjustments to specialized mounting hardware that is attached to the reactor vessel. When the temperature of these supporting structures increases due to the high temperature process that is occurring inside the vessel, the optical alignment can often suffer due to the thermal expansion of the mounting structure. This can render them useless especially for gas velocity measurements or other situations where precise optical alignment is required. What is needed is an optical probe that can be inserted into any hazardous environment that will not suffer alignment problems or other failure modes that are related to high temperature dirty environments, and at the same time maintain a clean optical surface through the lifetime of the devise so that it may be continually used for optical inspection or for control system applications. This paper describes details of the construction and the use of a transpiration purged optical probe which mitigates the problems that are outlined above. The transpiration probe may be used as either an emitter or a detector. The probe is implemented in the harsh high temperature environment of the NETL pulsed combustion system where products of combustion and particulate matter have been shown to degrade the performance of a normal optical window. Assessments of combustion heat release are made by monitoring the ultraviolet signatures that are produced by the concentration of OH during a pulsed combustion process. It is shown that these measurements are directly correlated with the pressure within the pulsed combustor. Probe temperature measurements are also presented to show how the probe and its mounting hardware remain at constant temperatures well below the high temperature environment which they monitor.« less

Authors:
; ;
Publication Date:
Research Org.:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
Sponsoring Org.:
USDOE - Office of Fossil Energy (FE)
OSTI Identifier:
921897
Report Number(s):
DOE/NETL-IR-2007-195
Journal ID: 0277-786X; TRN: US0800818
DOE Contract Number:  
None cited
Resource Type:
Conference
Journal Name:
Proceedings of SPIE (Sensors for Harsh Environments III, ed. by Hai Xiao, Anbo Wang, ISBN: 9780819469175)
Additional Journal Information:
Journal Volume: 6757; Conference: SPIE Optics East Conference and Exhibit, Boston, MA, Sept. 9-12, 2007
Publisher:
The International Society for Optical Engineering (SPIE), Bellingham WA
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; ALIGNMENT; COMBUSTION; COMBUSTION CHAMBERS; COMBUSTION HEAT; CONTROL SYSTEMS; FLUIDIZED BEDS; HEAT EXCHANGERS; MONITORING; POWER PLANTS; PROBES; REACTOR VESSELS; TEMPERATURE MEASUREMENT; THERMAL EXPANSION; TRANSPIRATION

Citation Formats

VanOsdol, J G, Woodruff, S D, and Straub, D L. Transpiration-purged optical probe: a novel sensor for high temperature harsh environments. United States: N. p., 2007. Web. doi:10.1117/12.735648.
VanOsdol, J G, Woodruff, S D, & Straub, D L. Transpiration-purged optical probe: a novel sensor for high temperature harsh environments. United States. https://doi.org/10.1117/12.735648
VanOsdol, J G, Woodruff, S D, and Straub, D L. 2007. "Transpiration-purged optical probe: a novel sensor for high temperature harsh environments". United States. https://doi.org/10.1117/12.735648.
@article{osti_921897,
title = {Transpiration-purged optical probe: a novel sensor for high temperature harsh environments},
author = {VanOsdol, J G and Woodruff, S D and Straub, D L},
abstractNote = {Typical control systems that are found in modern power plants must control the many physical aspects of the complex processes that occur inside the various components of the power plant. As detection and monitoring of pollutants becomes increasingly important to plant operation, these control systems will become increasingly complex, and will depend upon accurate monitoring of the concentration levels of the various chemical species that are found in the gas streams. In many cases this monitoring can be done optically. Optical access can also be used to measure thermal emissions and the particulate loading levels in the fluid streams. Some typical environments were optical access is needed are combustion chambers, reactor vessels, the gas and solid flows in fluidized beds, hot gas filters and heat exchangers. These applications all have harsh environments that are at high temperatures and pressures. They are often laden with products of combustion and other fine particulate matter which is destructive to any optical window that could be used to monitor the processes in these environments in order to apply some control scheme over the process. The dust and char that normally collects on the optical surfaces reduces the optical quality and thus impairs the ability of the optical surface to transmit data. Once this has occurred, there is generally no way to clean the optical surface during operation. The probe must be dismounted from the vessel, disassembled and cleaned or replaced, then remounted. This would require the shutdown of the particular component of the plant where optical monitoring is required. This renders the probe ineffective to be used as the monitoring part of any control system application. The components of optical monitoring equipment are usually built in supporting structures that require precise alignment. This is almost always accomplished using fine scale adjustments to specialized mounting hardware that is attached to the reactor vessel. When the temperature of these supporting structures increases due to the high temperature process that is occurring inside the vessel, the optical alignment can often suffer due to the thermal expansion of the mounting structure. This can render them useless especially for gas velocity measurements or other situations where precise optical alignment is required. What is needed is an optical probe that can be inserted into any hazardous environment that will not suffer alignment problems or other failure modes that are related to high temperature dirty environments, and at the same time maintain a clean optical surface through the lifetime of the devise so that it may be continually used for optical inspection or for control system applications. This paper describes details of the construction and the use of a transpiration purged optical probe which mitigates the problems that are outlined above. The transpiration probe may be used as either an emitter or a detector. The probe is implemented in the harsh high temperature environment of the NETL pulsed combustion system where products of combustion and particulate matter have been shown to degrade the performance of a normal optical window. Assessments of combustion heat release are made by monitoring the ultraviolet signatures that are produced by the concentration of OH during a pulsed combustion process. It is shown that these measurements are directly correlated with the pressure within the pulsed combustor. Probe temperature measurements are also presented to show how the probe and its mounting hardware remain at constant temperatures well below the high temperature environment which they monitor.},
doi = {10.1117/12.735648},
url = {https://www.osti.gov/biblio/921897}, journal = {Proceedings of SPIE (Sensors for Harsh Environments III, ed. by Hai Xiao, Anbo Wang, ISBN: 9780819469175)},
number = ,
volume = 6757,
place = {United States},
year = {Fri Oct 05 00:00:00 EDT 2007},
month = {Fri Oct 05 00:00:00 EDT 2007}
}

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