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Thermal measurement and degradation quantification of teeming ladle refractories and the effects on the process / LIAM COTTON

Swansea University Author: LIAM, COTTON

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DOI (Published version): 10.23889/SUthesis.58288

Abstract

The key objective of the thesis was to quantify the heat loss caused to the liquid steel due to the cooling effect of the teeming ladle refractories. It was previously hypothesised that the in-situ degradation of insulation layer would increase this cooling effect. To determine the cooling effect of...

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Published: Swansea 2021
Institution: Swansea University
Degree level: Doctoral
Degree name: EngD
Supervisor: Pleydell-Pearce, Cameron ; Abdallah, Zakaria
URI: https://cronfa.swan.ac.uk/Record/cronfa58288
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first_indexed 2021-10-11T09:28:02Z
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fullrecord <?xml version="1.0"?><rfc1807><datestamp>2021-10-11T10:56:09.7071610</datestamp><bib-version>v2</bib-version><id>58288</id><entry>2021-10-11</entry><title>Thermal measurement and degradation quantification of teeming ladle refractories and the effects on the process</title><swanseaauthors><author><sid>16a6bfa06768a75475d3b66d95b6aeaa</sid><firstname>LIAM</firstname><surname>COTTON</surname><name>LIAM COTTON</name><active>true</active><ethesisStudent>false</ethesisStudent></author></swanseaauthors><date>2021-10-11</date><abstract>The key objective of the thesis was to quantify the heat loss caused to the liquid steel due to the cooling effect of the teeming ladle refractories. It was previously hypothesised that the in-situ degradation of insulation layer would increase this cooling effect. To determine the cooling effect of the degraded insulation material it was first thermally characterised with in-situ thermocouple measurements. Post-mortem samples were recovered from the teeming ladles used for the thermocouple measurements during their regular production cycles in a BOS plant. The post-mortem samples were then tested for their thermophysical properties. From this it was possible to determine the density increased from 260kg/m3 to 759.6 kg/m3, the thermal conductivity increased from 0.039W/m.K to 0.15W/m.K and the specific heat capacity decreased by 40% compared to its original state. These findings were then used to calculate the increased heat loss rate of the refractory material in the teeming ladle, which then in turn causes increased heat loss to the steel transported by the ladle. A thermal model was used to determine the heat flux stored in a fully saturated ladle and then different time periods of cooling with and without a lid. The effect of teeming ladle lids reduced the heat losses by up to 11&#xB0;C per cycle compared to a ladle without a lid. Whereas the heat loss due to the insulative layer degradation was calculated to be &lt;1&#xB0;C for the initial heats before the ladle reached production temperatures and, therefore, had minimal effect. However, the degradation did show an increase in teeming ladle shell temperatures, which needs to be taken into account for service temperature monitoring. The thermal profiles of the modelled scenarios showed that if an accurate hot face measurement could be achieved it would be possible to accurately predict the cooling effect of each teeming ladle in production. This study was able to accurately measure the refractories and slag taken from a teeming and utilise the geometry of the ladle to reduce the error from thermal imaging. Previously predictions were used that could cause errors up to &#xB1;175&#xB0;C when taking thermal images of the teeming ladle hot face. Through the method adopted in this study it was possible to take accurate measurements of the hot face within &#xB1;5&#xB0;C. This can now be utilised by a thermal model to make accurate real time predictions of the heat loss caused by teeming ladle refractories. Thereby reducing the reheating required and improving the quality of steel produced.</abstract><type>E-Thesis</type><journal/><volume/><journalNumber/><paginationStart/><paginationEnd/><publisher/><placeOfPublication>Swansea</placeOfPublication><isbnPrint/><isbnElectronic/><issnPrint/><issnElectronic/><keywords/><publishedDay>11</publishedDay><publishedMonth>10</publishedMonth><publishedYear>2021</publishedYear><publishedDate>2021-10-11</publishedDate><doi>10.23889/SUthesis.58288</doi><url/><notes/><college>COLLEGE NANME</college><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><supervisor>Pleydell-Pearce, Cameron ; Abdallah, Zakaria</supervisor><degreelevel>Doctoral</degreelevel><degreename>EngD</degreename><apcterm/><lastEdited>2021-10-11T10:56:09.7071610</lastEdited><Created>2021-10-11T10:23:53.5031652</Created><path><level id="1">College of Engineering</level><level id="2">Engineering</level></path><authors><author><firstname>LIAM</firstname><surname>COTTON</surname><order>1</order></author></authors><documents><document><filename>58288__21131__8ecdfbaf5c7443ecbb05128643abcd1e.pdf</filename><originalFilename>Cotton_Liam_EngD_Thesis_Final_Redacted_Signature.pdf</originalFilename><uploaded>2021-10-11T10:34:42.8040455</uploaded><type>Output</type><contentLength>9125518</contentLength><contentType>application/pdf</contentType><version>E-Thesis &#x2013; open access</version><cronfaStatus>true</cronfaStatus><documentNotes>Copyright: The author, Liam Cotton, 2021.</documentNotes><copyrightCorrect>true</copyrightCorrect><language>eng</language></document></documents><OutputDurs/></rfc1807>
spelling 2021-10-11T10:56:09.7071610 v2 58288 2021-10-11 Thermal measurement and degradation quantification of teeming ladle refractories and the effects on the process 16a6bfa06768a75475d3b66d95b6aeaa LIAM COTTON LIAM COTTON true false 2021-10-11 The key objective of the thesis was to quantify the heat loss caused to the liquid steel due to the cooling effect of the teeming ladle refractories. It was previously hypothesised that the in-situ degradation of insulation layer would increase this cooling effect. To determine the cooling effect of the degraded insulation material it was first thermally characterised with in-situ thermocouple measurements. Post-mortem samples were recovered from the teeming ladles used for the thermocouple measurements during their regular production cycles in a BOS plant. The post-mortem samples were then tested for their thermophysical properties. From this it was possible to determine the density increased from 260kg/m3 to 759.6 kg/m3, the thermal conductivity increased from 0.039W/m.K to 0.15W/m.K and the specific heat capacity decreased by 40% compared to its original state. These findings were then used to calculate the increased heat loss rate of the refractory material in the teeming ladle, which then in turn causes increased heat loss to the steel transported by the ladle. A thermal model was used to determine the heat flux stored in a fully saturated ladle and then different time periods of cooling with and without a lid. The effect of teeming ladle lids reduced the heat losses by up to 11°C per cycle compared to a ladle without a lid. Whereas the heat loss due to the insulative layer degradation was calculated to be <1°C for the initial heats before the ladle reached production temperatures and, therefore, had minimal effect. However, the degradation did show an increase in teeming ladle shell temperatures, which needs to be taken into account for service temperature monitoring. The thermal profiles of the modelled scenarios showed that if an accurate hot face measurement could be achieved it would be possible to accurately predict the cooling effect of each teeming ladle in production. This study was able to accurately measure the refractories and slag taken from a teeming and utilise the geometry of the ladle to reduce the error from thermal imaging. Previously predictions were used that could cause errors up to ±175°C when taking thermal images of the teeming ladle hot face. Through the method adopted in this study it was possible to take accurate measurements of the hot face within ±5°C. This can now be utilised by a thermal model to make accurate real time predictions of the heat loss caused by teeming ladle refractories. Thereby reducing the reheating required and improving the quality of steel produced. E-Thesis Swansea 11 10 2021 2021-10-11 10.23889/SUthesis.58288 COLLEGE NANME COLLEGE CODE Swansea University Pleydell-Pearce, Cameron ; Abdallah, Zakaria Doctoral EngD 2021-10-11T10:56:09.7071610 2021-10-11T10:23:53.5031652 College of Engineering Engineering LIAM COTTON 1 58288__21131__8ecdfbaf5c7443ecbb05128643abcd1e.pdf Cotton_Liam_EngD_Thesis_Final_Redacted_Signature.pdf 2021-10-11T10:34:42.8040455 Output 9125518 application/pdf E-Thesis – open access true Copyright: The author, Liam Cotton, 2021. true eng
title Thermal measurement and degradation quantification of teeming ladle refractories and the effects on the process
spellingShingle Thermal measurement and degradation quantification of teeming ladle refractories and the effects on the process
LIAM, COTTON
title_short Thermal measurement and degradation quantification of teeming ladle refractories and the effects on the process
title_full Thermal measurement and degradation quantification of teeming ladle refractories and the effects on the process
title_fullStr Thermal measurement and degradation quantification of teeming ladle refractories and the effects on the process
title_full_unstemmed Thermal measurement and degradation quantification of teeming ladle refractories and the effects on the process
title_sort Thermal measurement and degradation quantification of teeming ladle refractories and the effects on the process
author_id_str_mv 16a6bfa06768a75475d3b66d95b6aeaa
author_id_fullname_str_mv 16a6bfa06768a75475d3b66d95b6aeaa_***_LIAM, COTTON
author LIAM, COTTON
author2 LIAM COTTON
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publishDate 2021
institution Swansea University
doi_str_mv 10.23889/SUthesis.58288
college_str College of Engineering
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hierarchy_top_id collegeofengineering
hierarchy_top_title College of Engineering
hierarchy_parent_id collegeofengineering
hierarchy_parent_title College of Engineering
department_str Engineering{{{_:::_}}}College of Engineering{{{_:::_}}}Engineering
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description The key objective of the thesis was to quantify the heat loss caused to the liquid steel due to the cooling effect of the teeming ladle refractories. It was previously hypothesised that the in-situ degradation of insulation layer would increase this cooling effect. To determine the cooling effect of the degraded insulation material it was first thermally characterised with in-situ thermocouple measurements. Post-mortem samples were recovered from the teeming ladles used for the thermocouple measurements during their regular production cycles in a BOS plant. The post-mortem samples were then tested for their thermophysical properties. From this it was possible to determine the density increased from 260kg/m3 to 759.6 kg/m3, the thermal conductivity increased from 0.039W/m.K to 0.15W/m.K and the specific heat capacity decreased by 40% compared to its original state. These findings were then used to calculate the increased heat loss rate of the refractory material in the teeming ladle, which then in turn causes increased heat loss to the steel transported by the ladle. A thermal model was used to determine the heat flux stored in a fully saturated ladle and then different time periods of cooling with and without a lid. The effect of teeming ladle lids reduced the heat losses by up to 11°C per cycle compared to a ladle without a lid. Whereas the heat loss due to the insulative layer degradation was calculated to be <1°C for the initial heats before the ladle reached production temperatures and, therefore, had minimal effect. However, the degradation did show an increase in teeming ladle shell temperatures, which needs to be taken into account for service temperature monitoring. The thermal profiles of the modelled scenarios showed that if an accurate hot face measurement could be achieved it would be possible to accurately predict the cooling effect of each teeming ladle in production. This study was able to accurately measure the refractories and slag taken from a teeming and utilise the geometry of the ladle to reduce the error from thermal imaging. Previously predictions were used that could cause errors up to ±175°C when taking thermal images of the teeming ladle hot face. Through the method adopted in this study it was possible to take accurate measurements of the hot face within ±5°C. This can now be utilised by a thermal model to make accurate real time predictions of the heat loss caused by teeming ladle refractories. Thereby reducing the reheating required and improving the quality of steel produced.
published_date 2021-10-11T04:18:04Z
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