Thesis (PhD)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: This study describes the design, construction, complete industrialisation and
operation of a dual bed vacuum swing adsorption (VSA) demonstration plant,
which operates at atmospheric and sub-atmospheric conditions. All design
objectives as set out initially were met. The plant removes contaminants such
as methanol and water from neutral wine spirit. Neutral wine spirit is a key
component of various local and international spirituous products which include
liqueurs, gin, vodka, fortified wines and brandy.
Neutral wine spirit can chemically be described as the azeotropic mixture of
ethanol and water, which occurs at an ethanol content of 96.4 vol. %.
Methanol is naturally present in all products from the vine. Fermentation and
distillation concentrate methanol even more, and due to physical and
chemical characteristics, its separation consumes as much as 45 % of total
production costs. Neutral wine spirit is produced by the proven technology of
continuous atmospheric distillation. Continuous improvement of the distillation
process is limited due to the physical constraints of an old facility, but also due
to previous design philosophies and approaches.
The VSA plant consists of two adsorbers, packed to a total height of
1.71 m and a diameter of 0.4 m. Adsorption took place at 100 °C and
regeneration at the same bed temperature with purified nitrogen gas at 170 °C
and a vacuum of 17 kPa (abs). Experiments were divided into Group I and
Group II experiments. Group I investigated the ability to separate methanol
and water from the azeotrope and to which efficiency it occurred. It consisted
of 120 adsorption cycles of 5 minutes each and 60 samples were drawn for
analyses. Breakthrough was not allowed to occur. The azeotropic feed was
consistently dehydrated to a water content < 0.05 wt %, while methanol
was reduced to < 4 mg/100mLAA. The type of 3A molecular sieve
(MS 564 CS) was specifically selected to ensure analytic as well as
organoleptic compliance with the product specification. Molecular sieve 4A
was removed due to organoleptic problems with the product. Group" experiments were performed in the format of a sensitivity analysis.
The effects of various process parameters on the methanol breakthrough
curves were individually assessed. Eighteen experiments were performed
over a period of 8 days, with 86 samples drawn. The duration of an adsorption
cycle was 30 minutes, allowing methanol breakthrough to occur. Water was
preferentially adsorbed. Negative methanol bed loadings during high water
loadings confirmed that water was able to displace methanol molecules. In
the presence of water, molecular sieve 3A was capable of adsorbing
0.6 mg methanol/100mLAA, while in the absence of water with synthetically
dosed methanol, molecular sieve 3A achieved a maximum loading of
12.3 mg methanol/100mLAA. The latter corresponded with a maximum
methanol feed content of 1118 mg/100mLAA.
In general, quicker breakthrough occurred at higher flow rates and feed
concentrations. Continuous breakthrough caused bed contamination and a
24-hour thermal regeneration was performed following experiment 12. The
feed flow rate was increased from the theoretical 50 f/hr to 70 f/hr without any
additional capital layout. Selected process conditions were found to be
effective in continuously separating methanol from ethanol. Depending on the
strategy of integration, profitability studies shows a Return on Investment of
between 110.1% - 220.8% for the adsorption project.
Adsorption is superior to distillation in the separation of methanol. Due to the
level of innovation involved, it is recommended that the contents of this study
remain confidential and patent protection is to be extended. This dissertation
speaks to both the wine making as well as the chemical engineering fraternity.
It seeks to provide credibility to both parties, by clarifying the unknown issues
fundamental to the respective disciplines. / AFRIKAANSE OPSOMMING: Hierdie studie definieer die ontwerp, vervaardiging en volledige
industrialisasie van 'n dubbelbed vakuum adsorpsie demonstrasie aanleg
(VSA) wat by atmosferiese en sub-atmosferiese kondisies bedryf word. Alle
ontwerpsdoelwitte is bereik. Die aanleg verwyder selektief metanol en water
vanuit neutrale wynspiritus. Neutrale wynspiritus is 'n sleutelkomponent van
verskeie spiritualieë in die plaaslike en internasionale wyn en spiritus bedryf.
Hierdie produkte sluit in likeurs, jenewer, vodka, gefortifiseerde wyne en
brandewyn.
Chemies, kan neutrale wynspiritus beskryf word as die azeotropiese mengsel
van etanol en water teen 96.4 vol. %. Metanol het 'n natuurlike
teenwoordigheid in alle produkte vanaf die wynstok. Gisting en distillasie
konsentreer metanol tot 'n hoër mate en weens fisiese en chemiese
eienskappe word metanol teen hoë koste vanaf die etanol stroom geskei. Die
metanol verwyderingskomponent beloop soveel as 45 % van die
produksiekoste van die totale proses. Neutrale wynspiritus word deur die
gevestigde tegnologie van kontinue atmosferiese distillasie geproduseer.
Kontinue verbetering van die proses word beperk deur die fisiese ouderdom
en toestand van die fasiliteite, maar is ongelukkig ook die resultaat van vorige
ontwerpsfilosofieë en benaderings.
Die adsorbeerders is gepak tot 'n hoogte van 1.71 m met 'n deursnit van
0.4 m. Adsorpsie het by 100°C plaasgevind en regenerasie by dieselfde
bedtemperatuur met stikstofgas by 170°C en 'n vakuum van 17 kPa (abs).
Eksperimentele werk is in Groep I en Groep II eksperimente verdeel. Groep I
het die effektiewe prosesvermoë om metanol en water vanuit die azeotroop te
verwyder ondersoek. Dit het bestaan uit 120 adsorpsie siklusse van 5 minute
elk. Sestig monsters is getrek vir analise. Deurbreek van metanol was nie toe
gelaat om plaas te vind nie. Die azeotropiese toevoer is konsekwent tot 'n
water inhoud < 0.05 massa % gedehidrateer is. 'n Metanol inhoud < 4 mg/100 mLAA is bereik. Die tipe 3A molekulêre sif
(MS 564 CS) was spesifiek vir die toepassing geselekteer om sodoende 'n
analities sowel as organolepties aanvaarbare produk te lewer. Molekulêre sif
4A was verwyder weens die vorming van produk wangeure.
Groep II eksperimente is in die vorm van 'n sensitiwiteits analise uitgevoer.
Die effek van verskeie veranderlikes is individueel op die metanol
deurbreekkurwe getoets. Agtien eksperimente is oor 'n tydperk van 8 dae
gedoen, met 'n totaal van 86 monsters wat getrek is. 'n Adsorpsie siklus het
30 minute geduur en het deurbreek van metanol toegelaat. Water is by
voorkeur geadsorbeer. Negatiewe metanol bed ladings tydens hoë waterteenwoordigheid
toon dat water wel metanolmolekule op 'n adsorpsie-posisie
kan verplaas. In die teenwoordigheid van water is 'n bedlading van
0.6 mg metanol/100mLAA verkry, met 'n maksimum van
12.3 mg metanol/100mLAA in die afwesigheid van water. Laasgenoemde
verteenwoordig 'n toevoer met 'n metanol inhoud van 1118 mg/100mLAA.
In die algemeen is gevind dat 'n toename in toevoer vloeitempo en
konsentrasie die tyd vir deurbreek verkort. Kontinue deurbreek het
kontaminasie van die bed teweeg gebring en 'n termiese regenerasie is vir
24 ure na eksperiment 12 gedoen. Die teoretiese ontwerps vloeitempo was
50 .elhr, maar resultate het getoon dat die aanleg tot 70 .t'/hr kan verwerk
sonder addisionele koste. Die geselekteerde proseskondisies was effektief in
die versekering van die kontinue skeiding van metanol en etanol. Die
lewensvatbaarheidstudie toon, afhangende van die strategie van integrasie, 'n
Opbrengs op Belegging van tussen 110.1% - 220.8%.
Adsorpsie het 'n beter skeidingsvermoë as konvensionele distillasie vir die
verwydering van metanol vanuit etanol. Weens die vlak van innovasie
betrokke, word dit voorgestel dat die inhoud van hierdie studie vertroulik
gehou word en dat patent beskerming verleng sal word. Hierdie verhandeling
spreek tot beide die wynmaak sowel as chemiese ingenieurs dissiplines.
Daar is gepoog om geloofwaardigheid vir beide partye te skep deur die
onbekende aspekte van albei dissiplines aan te spreek.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52634 |
| Date | 03 1900 |
| Creators | Goliath, Elroy Mario |
| Contributors | Cloete, F. L. D., Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 242 p. : ill. |
| Rights | Stellenbosch University |
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