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Title: Avoiding Carbon Bed Hot Spots in Thermal Process Off-Gas Systems

Abstract

Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (radioactive and hazardous) wastes. Test programs performed in recent years have shown that mercury in off-gas streams from processes that treat radioactive wastes can be controlled using fixed beds of activated sulfur-impregnated carbon, to levels low enough to comply with air emission regulations such as the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards. Carbon bed hot spots or fires have occurred several times during these tests, and also during a remediation of tanks that contained mixed waste. Hot spots occur when localized areas in a carbon bed become heated to temperatures where oxidation occurs. This heating typically occurs due to heat of absoption of gas species onto the carbon, but it can also be caused through external means such as external heaters used to heat the carbon bed vessel. Hot spots, if not promptly mitigated, can grow into bed fires. Carbon bed hot spots and fires must be avoided in processes that treat radioactive and mixed waste. Hot spots are detected by (a) monitoring in-bed and bed outlet gas temperatures, and (b) more important, monitoringmore » of bed outlet gas CO concentrations. Hot spots are mitigated by (a) designing for appropriate in-bed gas velocity, for avoiding gas flow maldistribution, and for sufficient but not excessive bed depth, (b) appropriate monitoring and control of gas and bed temperatures and compositions, and (c) prompt implementation of corrective actions if bed hot spots are detected. Corrective actions must be implemented quickly if bed hot spots are detected, using a graded approach and sequence starting with corrective actions that are simple, quick, cause the least impact to the process, and are easiest to recover from.« less

Authors:
;
Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
DOE - EM
OSTI Identifier:
1017891
Report Number(s):
INL/CON-10-18125
TRN: US1103294
DOE Contract Number:  
DE-AC07-05ID14517
Resource Type:
Conference
Resource Relation:
Conference: 30th International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors,Jacksonville, Florida,05/10/2011,05/13/2011
Country of Publication:
United States
Language:
English
Subject:
12 MGMT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; ABSORPTION HEAT; CARBON; COMBUSTORS; GAS FLOW; HEATERS; HEATING; HOT SPOTS; IMPLEMENTATION; MERCURY; MONITORING; NUCLEAR FUELS; OFF-GAS SYSTEMS; OXIDATION; PACKED BEDS; RADIOACTIVE WASTES; REGULATIONS; REPROCESSING; TANKS; VELOCITY; WASTES; mercury; mixed waste treatment; nuclear fuel reprocessing

Citation Formats

Nick Soelberg, and Joe Enneking. Avoiding Carbon Bed Hot Spots in Thermal Process Off-Gas Systems. United States: N. p., 2011. Web.
Nick Soelberg, & Joe Enneking. Avoiding Carbon Bed Hot Spots in Thermal Process Off-Gas Systems. United States.
Nick Soelberg, and Joe Enneking. Sun . "Avoiding Carbon Bed Hot Spots in Thermal Process Off-Gas Systems". United States. https://www.osti.gov/servlets/purl/1017891.
@article{osti_1017891,
title = {Avoiding Carbon Bed Hot Spots in Thermal Process Off-Gas Systems},
author = {Nick Soelberg and Joe Enneking},
abstractNote = {Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (radioactive and hazardous) wastes. Test programs performed in recent years have shown that mercury in off-gas streams from processes that treat radioactive wastes can be controlled using fixed beds of activated sulfur-impregnated carbon, to levels low enough to comply with air emission regulations such as the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards. Carbon bed hot spots or fires have occurred several times during these tests, and also during a remediation of tanks that contained mixed waste. Hot spots occur when localized areas in a carbon bed become heated to temperatures where oxidation occurs. This heating typically occurs due to heat of absoption of gas species onto the carbon, but it can also be caused through external means such as external heaters used to heat the carbon bed vessel. Hot spots, if not promptly mitigated, can grow into bed fires. Carbon bed hot spots and fires must be avoided in processes that treat radioactive and mixed waste. Hot spots are detected by (a) monitoring in-bed and bed outlet gas temperatures, and (b) more important, monitoring of bed outlet gas CO concentrations. Hot spots are mitigated by (a) designing for appropriate in-bed gas velocity, for avoiding gas flow maldistribution, and for sufficient but not excessive bed depth, (b) appropriate monitoring and control of gas and bed temperatures and compositions, and (c) prompt implementation of corrective actions if bed hot spots are detected. Corrective actions must be implemented quickly if bed hot spots are detected, using a graded approach and sequence starting with corrective actions that are simple, quick, cause the least impact to the process, and are easiest to recover from.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2011},
month = {5}
}

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