Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2009. / 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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2901 |
| Date | 12 1900 |
| Creators | Sundstrom, Ashley William |
| Contributors | Eksteen, J. J., Aldrich, C., University of Stellenbosch. Faculty of Engineering. Dept. of Process Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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