Thesis (MScEng (Process Engineering))--Stellenbosch University, 2010. / ENGLISH ABSTRACT: Recently, improved technologies have been developed for the biobutanol fermentation
process: higher butanol concentrations and productivities are achieved during
fermentation, and separation and purification techniques are less energy intensive. This
may result in an economically viable process when compared to the petrochemical
pathway for butanol production. The objective of this study is to develop process models
to compare different possible process designs for biobutanol production from sugarcane
molasses. Some of the best improved strains, which include Clostridium acetobutylicum
PCSIR-10 and Clostridium beijerinckii BA101, produce total solvent concentrations of up to
24 g/L. Among the novel technologies for fermentation and downstream processing, fedbatch
fermentation with in situ product recovery by gas-stripping, followed by either
liquid-liquid extraction or adsorption, appears to be the most promising techniques for
current industrial application. Incorporating these technologies into a biorefinery
concept will contribute toward the development of an economically viable process. In
this study three process routes are developed. The first two process routes incorporate
well established industrial technologies: Process Route 1 consist of batch fermentation
and steam stripping distillation, while in Process Route 2, some of the distillation columns
is replaced with a liquid-liquid extraction column. The third process route incorporates
fed-batch fermentation and gas-stripping, an unproven technology on industrial scale.
Process modelling in ASPEN PLUS® and economic analyses in ASPEN Icarus® are performed
to determine the economic feasibility of these biobutanol production process designs.
Process Route 3 proved to be the only profitable design in current economic conditions.
For the latter process, the first order estimate of the total project capital cost is
$187 345 000.00 (IRR: 35.96%). Improved fermentation strains currently available are not
sufficient to attain a profitable process design without implementation of advanced
processing techniques. Gas stripping is shown to be the single most effective process
step (of those evaluated in this study) which can be employed on an industrial scale to
improve process economics of biobutanol production. / AFRIKAANSE OPSOMMING: Onlangse verbeteringe in die tegnologie vir die vervaardiging van butanol via die
fermentasie roete het tot gevolg dat: hoër butanol konsentrasies en produktiwiteit verkry
kan word tydens die fermentasie proses, en energie verbruik tydens skeiding-en
suiweringsprosesse laer is. Hierdie verbeteringe kan daartoe lei dat biobutanol op ʼn
ekonomiese vlak kan kompeteer met die petrochemiese vervaardigings proses vir
butanol. Die doelwit van die studie is om proses modelle te ontwikkel waarmee
verskillende proses ontwerpe vir die vervaardiging van biobutanol vanaf suikerriet
melasse vergelyk kan word. Verbeterde fermentasie organismes, wat insluit Clostridium
acetobutylicum PCSIR-10 en Clostridium beijerinckii BA101, het die vermoë om ABE
konsentrasies so hoog as 24 g/L te produseer. Wat nuwe tegnologie vir fermentasie en
skeidingprosesse behels, wil dit voorkom of wisselvoer fermentasie met gelyktydige
verwydering van produkte deur gasstroping, gevolg deur of vloeistof-vloeistof ekstraksie
of adsorpsie, van die mees belowende tegnieke is om tans in die nywerheid te
implementeer. Deur hierdie tegnologie in ʼn bioraffinadery konsep te inkorporeer sal
bydra tot die ontwikkeling van ʼn ekonomies lewensvatbare proses. Drie prosesserings
roetes word in die studie ontwikkel. Die eerste twee maak gebruik van goed gevestigde
industriële tegnologie: Proses Roete 1 implementeer enkellading fermentasie en stoom
stroping distillasie, terwyl in Proses Roete 2 van die distilasiekolomme vervang word met
ʼn vloeistof-vloeistof ekstraksiekolom. Die derde proses roete maak gebruik van
wisselvoer fermentasie met gelyktydige verwydering van produkte deur gas stroping. Die
tegnologie is nog nie in die nywerheid bewys of gevestig nie. Om die ekonomiese
uitvoerbaarheid van die proses ontwerpe te bepaal word proses modellering uitgevoer in
ASPEN PLUS® en ekonomiese analises in ASPEN Icarus® gedoen. Proses Roete 3 is die
enigste ontwerp wat winsgewend is in huidige ekonomiese toestande. Die eerste orde
koste beraming van die laasgenoemde projek se totale kapitale koste is $187 345 000.00
(opbrengskoers: 35.96%). Die verbeterde fermentasie organismes wat tans beskikbaar is,
is nie voldoende om ʼn proses winsgewend te maak nie; gevorderde proses tegnologie
moet geïmplementeer word. Gasstroping is bewys as die mees effektiewe proses stap
(getoets in die studie) wat op industriële skaal geïmplementeer kan word om die
winsgewendheid van die biobutanol proses te verbeter. / Centre for Renewable and Sustainable Energy Studies
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/4374 |
| Date | 03 1900 |
| Creators | Van der Merwe, Abraham Blignault |
| Contributors | Knoetze, J. H., Gorgens, J. F., Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 159 p. : ill. |
| Rights | Stellenbosch University |
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