The development of a simulative hybrid model for optimising the production of a high-carbon ferromanganese furnace.

Sundstrom, Ashley William (2009-12)

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2009.

Thesis

ENGLISH ABSTRACT: A project was initially commenced for optimising the production output at a specific high-carbon ferromanganese furnace. Since operational difficulties were experienced in this furnace and with a lack of reliable data for the year 2007, it was decided that data from a more stable high-carbon ferromanganese furnace should be analysed instead. Three key performance indicators (KPI’s) were selected to give an indication of overall process performance. These were: (1) the total tonnes of high-carbon ferromanganese produced per tonne of feed material, (2) the percentage recovery of manganese to the alloy product, and (3) the alloy:slag ratio. Maximisation of each of these would contribute to the overall improvement of the process. To achieve the objectives of the project, a hybrid model was developed to characterise the production behaviour of the furnace and to optimise the proposed KPI’s. The hybrid model consisted of two modelling branches, viz. equilibrium and dynamic modelling. An equilibrium sub-model was created and the output results were then used as inputs into a dynamic sub-model, which not only considered the effects of thermo-equilibrium interactions, but also the faster-changing electrical dynamics of furnace control. The final modelling step involved genetic optimisation, whereby model variables were manipulated to optimise the proposed KPI’s. In other words, operating conditions were established to improve furnace performance. It was determined that significant improvement in the values of the KPI’s may be expected if the optimised setpoints are implemented on-site. The existing setpoints for electrical operation should be maintained while the power expended per tonne of alloy should be altered (by tapping more regularly). Specific adjustments to the proportions of the feed recipe should also be made.

AFRIKAANSE OPSOMMING: ‘n Projek is aanvanklik begin om die produksieproses by ‘n spesifieke hoëkoolstof ferromangaanoond te optimiseer. Sedert operasionele probleme ondervind is in die oond en daar ‘n tekort is aan vertroubare data vir die jaar 2007, is daar besluit om data van ‘n meer stabiele hoëkoolstof ferromangaanoond te annaliseer. Drie sleutelverrigtingsaanwysers (SVA’s) is geselekteer om die algehele prosesverrigting aan te dui. Hulle is: (1) Die totale tonnemaat hoëkoolstof ferromangaan geproduseer per tonnemaat van voermateriaal, (2) die persentasie herwinning van mangaan tot die allooiproduk, en (3) die allooi:slak verhouding. Die verhoging van elk van die bogenoemde sal bydra tot die algehele bevordering van die proses. Om die doelwitte van die projek na te kom, is ‘n Kombinasiemodel ontwikkel om die produksie gedrag van die oond te karakteriseer en om die voorgestelde SVA’s te optimiseer. Die Kombinasiemodel het bestaan uit twee modelleringsvertakkings, nl. termodinamiese ewewig en dinamiese modellering. ‘n Termodinamiese ewewig submodel is geskep en die uitset resultate is gevolglik gebruik as invoerdata na ‘n dinamiese sub-model, wat nie slegs die uitwerking van termo-ewewiginteraksies in ag neem nie, maar ook die vinnigveranderende elektriese dinamika van die oond. Die finale modelleringstap het genetiese optimisering behels, waarby model veranderlikes gemanipuleer is om die voorgestelde SVA’s te optimiseer. Met ander woorde, operasionele kondisies is vasgestel om oond produksie te bevorder. Dit is bepaal dat kenmerkende verbetering in die waardes van die SVA’s verwag kan word as die ge-optimiseerde setpunte toegepas is op die oond. Die oorspronklike setpunte vir elektriese beheer hoort gehandhaaf te word terwyl die krag verbruik per ton allooi verander moet word (deur om meer gereeld te tap). Spesifieke verstellings op die proporsies van die voerresep moet ook gemaak word.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/2901
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