| 1. |
- Swartling, Maria, 1983-
(författare)
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A Study of the Heat Flow in the Blast Furnace Hearth Lining
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 2. |
- Dahlin, Anders
(författare)
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Influence of Ladle-slag Additions on BOF-Process Parameters
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The influence of ladle-slag additions on the BOF-process performance were investigated in plant trials. The aim of the study was to recycle ladle slag from secondary steelmaking to the LD-converter to save lime and improve the slag formation. More specifically, two plant trial campaigns covering in total 83 heats, whereof 47 with ladle-slag additions and 36 without ladle-slag additions, were performed. Slag and steel sampling of the process were performed at tapping as well as during blowing at 15, 35, and 65% of the total blowing time. During the first campaign, ladle slag was added through the chute and lime reductions were made manually to correct for the ladle-slag addition. In the second campaign, a development of the approach was made to suite a normal production practice. More specifically, the ladle slag was added through the weight-hopper system and implemented in the process-control system. In this way, the lime additions were reduced automatically by approximately 260 kg per heat. Moreover, the heat balance was compensated with a reduction in the iron-ore consumption. Additionally, the lance program was modified and the lance was lowered in the initial stages of the blow. On the positive side, it was found that no demerits in the metallurgical performance of the process occur when ladle slag is recycled to the BOF-process. Furthermore, only slight affections on the slag composition were found, mainly with respect to the Al2O3 and FeO-content. In addition, the ladle slag was shown to melt during the initial stages of the blow. This contributed to an increased slag weight both during the blow and at tapping. However, a negative effect on the blowing time was experienced during the trials. Although, this effect was more pronounced during the first campaign and could be reduced with a controlled heat balance during the second campaign.
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| 3. |
- Wei, Wenjing, et al.
(författare)
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Energy Consumption and Greenhouse Gas Emissions of High-Carbon Ferrochrome Production
- 2023
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Ingår i: JOM. - : Springer Nature. - 1047-4838 .- 1543-1851. ; 75:4, s. 1206-1220
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- This work presents a process model developed based on mass and energy conservation to assess high carbon ferrochrome production from cradle to gate through four supply routes: (1) a conventional submerged arc furnace (SAF), (2) a closed submerged arc furnace with preheating (CSAF+PH), (3) a closed submerged arc furnace with 60% prereduction (CSAF+PR60%) and (4) a direct-current arc furnace (DCAF). The energy requirements are between 40 and 59 GJ/t FeCr (74–111 GJ/t Cr), and the greenhouse gas (GHG) emissions range between 1.8 and 5.5 tCO2-eq/t FeCr (3.3–10.3 tCO2-eq/t Cr). The upgrading of coal-powered SAF process to a closed furnace CSAF+PH and CSAF+PR60% contributes to an emission reduction of 23% and 18%, respectively. Moreover, the use of hydro-powered electricity leads to a further emission reduction of 68% and 47%, respectively. For CSAF+PR process, the GHG emissions can be reduced by 14% when increasing the pre-reduction ratio from 30% to 80% and decreased by 10% when charging hotter feed from 100 °C to 1000 °C. The proposed process model is feasible in generating site-specific inventory data and allowing for parameter studies as well as supporting companies to improve the transparency of the environmental performance in the FeCr value chain.
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