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A Study of the Heat Flow in the Blast Furnace Hearth Lining
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aim of the present thesis was to study the heat flows in the blast furnace hearth lining by experimental measurements and numerical modeling. Thermocouple data from an operating furnace have been used throughout the work, to verify results and to develop methodologies to use the results in further studies. The hearth lining were divided into two zones based on the thermocouple readings: a region with regular temperature variations due to the tapping of the furnace, and another region with slow temperature variations. In an experimental study, the temperatures of the outer surfaces of the wall and bottom were measured and compared with lining temperature measured by thermocouples. Expressions to describe the outer surface temperature profiles were derived and used as input in a two-dimensional steady state heat transfer model. The aim of the study was to predict the lining temperature profiles in the region subjected to slow temperature variations. The methodology to calculate a steady state lining temperature profile was used as input to a three-dimensional model. The aim of the three-dimensional model was primarily to study the region with dynamic lining temperature variations caused by regular tappings. The study revealed that the replacement of original lining with tap clay has an effect when simulating the quasi-stationary temperature variations in the lining. The study initiated a more detailed study of the taphole region and the size and shape of the tap clay layer profile. It was concluded, that in order to make a more accurate heat transfer model of the blast furnace hearth, the presence of a skull build-up below the taphole, erosion above the taphole and the bath level variations must to be taken into consideration.

Place, publisher, year, edition, pages
Stockholm: KTH , 2010. , xiv, 51 p.
Keyword [en]
Blast furnace, heat transfer, mathematical model, experimental
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-13163ISBN: 978-91-7415-677-5 (print)OAI: oai:DiVA.org:kth-13163DiVA: diva2:321371
Public defence
2010-06-11, F3, Lindstedtsvägen 26, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
QC 20100706Available from: 2010-05-31 Created: 2010-05-31 Last updated: 2010-12-03Bibliographically approved
List of papers
1. Experimentally determined temperatures in blast furnace hearth
Open this publication in new window or tab >>Experimentally determined temperatures in blast furnace hearth
2010 (English)In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 37, no 1, 21-26 p.Article in journal (Refereed) Published
Abstract [en]

In this study temperature measurements have been carried out at blast furnace no. 2 at SSAB Oxelosund. The temperature was measured in the hearth lining and at the outer surfaces of the hearth wall and bottom. The lining temperature was measured using permanently installed thermocouples and surface temperatures were measured using a hand held thermocouple. The aims of the study were to find a correlation between lining and surface temperatures as well as to find a method to determine the surface temperature based on readings from lining thermocouples. The overall conclusion is that the bottom and wall surface temperatures can be determined based on lining temperatures.

Keyword
Blast furnace, Hearth, Temperature, Measurements, Lining, Surface, HEAT-TRANSFER, MODEL, STATE
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-13963 (URN)10.1179/030192309X12506804200627 (DOI)000273918200004 ()2-s2.0-77949444880 (Scopus ID)
Note
QC 20100706Available from: 2010-07-06 Created: 2010-07-05 Last updated: 2017-12-12Bibliographically approved
2. Heat Transfer Modelling of a Blast Furnace Hearth
Open this publication in new window or tab >>Heat Transfer Modelling of a Blast Furnace Hearth
2010 (English)In: STEEL RES INT, ISSN 1611-3683, Vol. 81, no 3, 186-196 p.Article in journal (Refereed) Published
Abstract [en]

This paper describes the development of a heat transfer model with the purpose of studying the heat flows in the hearth of an operating blast furnace. Temperature profiles were calculated for a period of time to study the transition from steady blast furnace operation to an unsteady period, and back to a steady period. This total time period had the highest lining temperatures registered since the beginning of the current campaign. It was concluded that no part of the lining had an inner temperature higher than the critical temperature of 1150 degrees C. Thus, no refractory could have been in direct contact with slag or iron. The corner between the wall and the bottom was identified to be the most sensitive part of the lining. It is suggested that thermocouples are installed in this area, to improve the temperature control.

Keyword
Blast furnace, modelling, heat transfer, hearth, measurements, STATE, TEMPERATURE, OPERATION
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-13962 (URN)10.1002/srin.200900145 (DOI)000276297800003 ()2-s2.0-77952124378 (Scopus ID)
Note
QC 20100706 Tidigare titel: Heat transfer modeling of a blast furnace hearthAvailable from: 2010-07-06 Created: 2010-07-05 Last updated: 2010-11-24Bibliographically approved
3. Short-term Lining Temperature Changes during Tapping in a Blast Furnace
Open this publication in new window or tab >>Short-term Lining Temperature Changes during Tapping in a Blast Furnace
2010 (English)In: Steel Research International, ISSN 1611-3683, Vol. 81, no 9, 724-734 p.Article in journal (Refereed) Published
Abstract [en]

The following paper presents a three-dimensional heat transfer model of the blast furnace hearth. The model has been developed with the objective of studying the short term changes in lining temperature during regular tappings. It is based on the actual conditions of Blast Furnace No. 2 at SSAB Oxelosund in Sweden. The model was evaluated and analysed using thermocouple data from the operating furnace. The study showed that a layer of tap clay around the tap hole had a significant effect on the heat transfer by reducing the heat variations in the lining. More specifically, a layer of 10-15 cm gave the best correlation between calculated and thermocouple data. A simulation was performed where the melt temperature and the tap cycle duration was based on process data from the operating furnace. Moreover, the size of the area subjected to changes due to the regular tappings was defined. It was found to be the region within an angle of 13 degrees from the tap hole, 0.9 m above and 0.8 m below the tap hole.

Keyword
Blast furnace, mathematical model, heat transfer, taphole, tap cycles, tap clay
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-13976 (URN)10.1002/srin.201000035 (DOI)000281912200005 ()2-s2.0-77956577386 (Scopus ID)
Note
QC 20100706. Uppdaterad från accepted till published (20101203).Available from: 2010-07-06 Created: 2010-07-06 Last updated: 2010-12-03Bibliographically approved
4. A Study of Dynamic Lining Temperature Variations in the Taphole Region of a Blast Furnace
Open this publication in new window or tab >>A Study of Dynamic Lining Temperature Variations in the Taphole Region of a Blast Furnace
(English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArticle in journal (Other academic) Submitted
Abstract [en]

The thermal behavior of the blast furnace hearth with special focus on the taphole regionwas studied. The original lining is in this region assumed to be replaced with tap clay,which influences the dynamic lining temperature variations. A heat transfer modelpreviously developed has been used to study the effect of the size and shape of the tapclay layer around the taphole. Four different cases have been calculated: one referencecase and three cases different tap clay layer geometries. It was found that the calculatedpeak-to-peak amplitudes of the lining temperatures during the tap cycles at the location ofa thermocouple can be approximated as a linear function of the tap clay layer thicknessesfor all calculated cases: the R2-value of the linear approximations were in the range 0.9-0.98. Modeling was also done where both the 90th and the 10th percentile of the observedpeak-to-peak values of the studied tap cycles were included to describe the behavior ofthe operating furnace. The calculation results show that the taphole region can be dividedinto three categories based on how well the model can describe the measured processdata: below, at and above taphole level. Below the taphole level, the measured liningtemperature variations are smaller than for the calculated results. At the taphole level, themodel can describe the behavior of the operating furnace. Above the taphole level, themeasured lining temperature variations are larger than for the calculated results. It wasconcluded, that in order to make a more accurate heat transfer model of the tapholeregion, the presence of a skull build-up below the taphole, erosion above the taphole andthe bath level variations need to be taken into account.

Keyword
Blast furnace, mathematical model, heat transfer, taphole, tap cycles, tap clay
Identifiers
urn:nbn:se:kth:diva-13977 (URN)
Note

QC20100706

Available from: 2010-07-06 Created: 2010-07-06 Last updated: 2017-12-12Bibliographically approved

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