{"title":"CFD Modelling of Inconsistent Furnace Taps","authors":"J. Olsen","doi":"10.2139/ssrn.3926099","DOIUrl":"https://doi.org/10.2139/ssrn.3926099","url":null,"abstract":"During tapping of ferroalloys, significant variations between consecutive taps are observed. This inconsistency is not properly understood. It has been hypothesized that the inconsistencies are caused by changes in furnace conditions between taps. The configuration of particles in the burden consisting of coke and minerals can change due to forces exerted during closing and opening of tap-holes or due to other movements in the particle bed. Earlier studies with CFD have not revealed any inconsistent tapping since they have assumed non-varying and often ideal uniform particle bed configurations. Here a sensitivity study is presented where particle conditions are non-uniform and these represent configurations which could represent real consecutive variations. The results show that large variations between taps will happen if there is a small variation in particle bed configuration close to the tap-hole entrance. In this region variations are likely due to the forces exerted during opening and closing of tap-holes.","PeriodicalId":203738,"journal":{"name":"INFACON XVI 2021: Furnace Modelling","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128617294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Fromreide, S. A. Halvorsen, M. Sparta, V. Risinggård, P. Salgado, D. Gómez, E. Herland
{"title":"Effects of Alternating Currents in the Hearth of Submerged Arc Furnaces","authors":"M. Fromreide, S. A. Halvorsen, M. Sparta, V. Risinggård, P. Salgado, D. Gómez, E. Herland","doi":"10.2139/ssrn.3926716","DOIUrl":"https://doi.org/10.2139/ssrn.3926716","url":null,"abstract":"It is well known that alternating currents (AC) differ significantly from direct currents (DC) in large electrodes for Submerged Arc Furnaces (SAFs). The skin effect concentrates AC to the periphery of each electrode, while the proximity effect causes higher current concentration towards the leading electrode. In a presentation at INFACON XV it was further shown that there is also a significant proximity effect between electrode currents and induced currents in the furnace steel shell. Here, we will focus on differences and similarities between AC and DC below the electrodes. In many processes the current runs primarily vertically in a coke bed from each electrode to a metal bath, where it distributes to the other electrodes. In such coke beds we find no significant difference between AC and DC. In the highly conductive metal, there will be horizontal currents and a significant AC skin effect. Horizontal currents will also be present in the materials above the metal, depending on the electrical conductivity in this region. A simple model shows that there is a strong proximity effect between such adjacent currents, “pushing” the currents upwards within the slag/coke bed region. A simple estimate, based on furnace dimensions and assumed conductivities, will show whether this effect is significant, in which case DC computations are inadequate to estimate the current paths. The same proximity effect will significantly enhance induced currents in an electrically conductive lining. Finally, since the underlying Maxwell’s equations are linear, the fundamental current paths in 3-phase AC SAFs can be studied by computing two independent single-phase cases for a given geometry and distribution of electrical conductivities. Any other current distribution will be a linear combination of these two solutions.","PeriodicalId":203738,"journal":{"name":"INFACON XVI 2021: Furnace Modelling","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129961961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}