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The measurement and modelling of low-pressure phase equilibrium data for 1-alcohols + n-alkanes
Thesis (MEng)--Stellenbosch University, 2022.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2022
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| _version_ | 1867614013072867328 |
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| access_status_str | Open Access |
| author | du Plessis, Susanna Hendrina |
| author2 | Schwarz, Cara Elsbeth |
| author_browse | Schwarz, Cara Elsbeth du Plessis, Susanna Hendrina |
| author_facet | Schwarz, Cara Elsbeth du Plessis, Susanna Hendrina |
| author_sort | du Plessis, Susanna Hendrina |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/124877 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:45:16.097Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/124877 The measurement and modelling of low-pressure phase equilibrium data for 1-alcohols + n-alkanes du Plessis, Susanna Hendrina Schwarz, Cara Elsbeth Latsky, Carla Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. Thermodynamics Low-pressure Vapour-liquid equilibrium Manufacturing processes Thesis (MEng)--Stellenbosch University, 2022. ENGLISH SUMMARY: The production processes for detergent range 1-alcohols generally produce product streams containing unreacted n-alkanes. These detergent range alcohols are widely utilised in several industries. The purity of the 1-alcohols is therefore imperative. This necessitates efficient post-production separation of the 1-alcohols and n-alkanes. Due to similar boiling and melting temperatures, traditional separation processes are ineffective, and thus advanced separation techniques are required. Several studies have shown supercritical fluid fractionation (SFF) to be a feasible alternative. The effective design of SFF processes require reliable phase equilibrium data and knowledge of appropriate thermodynamic models that can accurately correlate or predict the phase behaviour. This study aimed to investigate the binary vapour liquid equilibrium (VLE) data for 1-alcohol + n-alkane systems, in which the n-alkane is 3-, 2- and 1-carbon larger than the 1-alcohol. This aim was achieved by experimentally measuring fifteen new binary VLE datasets at sub-atmospheric pressure (40 kPa), interpreting the trends observed for these systems and modelling the newly measured data in Aspen Plus®. Data were measured for 1-alcohols ranging between C5 – C10 and n-alkanes ranging between C8 – C13 by means of a dynamic-analytical technique. This data served to complement a previous study that measured data for 1-alcohols ranging between C5 – C10 and n-alkanes ranging between C9 – C14. The reliability and accuracy of the newly measured data were validated by verifying the methodology and therefore data for well-documented literature systems were reproduced. Additionally, the thermodynamic consistency of the data was evaluated by means of the L-W, McDermott-Ellis and Fredenslund tests. The newly measured data exhibited strong positive deviations from ideality, whilst close-boiling combinations presented temperature-minimum azeotropes. Several consistent trends were observed for the data. The departure from ideality decreased, and the azeotropic composition shifted in the direction of the 1-alcohol rich region, as the carbon chain length of the pure components increased within each group of data. Between groups of systems, the departure from ideality increased, and the azeotropic composition shifted in the direction of the 1-alcohol rich region, as the difference between the carbon chain lengths increased from one to four carbons. The data were modelled in Aspen Plus® using the non-random two-liquid (NRTL) model, predictive Soave-Redlich-Kwong (PSRK) + UNIFAC and PSRK + NRTL models. The NRTL model outperformed the other models, correlating the data very well. The PSRK + UNIFAC model reasonably predicted lower homolog combinations, depending on the accuracy of the Mathias-Copeman parameters, but failed to accurately predict higher homolog combinations. The PSRK + NRTL model improved the predictions of the PSRK + UNIFAC model, incorporating regressed NRTL binary interaction parameters. Future work should consider investigating the CnOH + nCn+5 systems, to evaluate the ability to extrapolate the trends observed in this study to other groups of systems. Further modelling is also required, to evaluate if low-pressure interaction parameters determined from these data, have the ability to accurately represent high-pressure data. AFRIKAANS SUMMARY: Die produksie van 1-alkohole wat in die skoonmaak- en reinigermiddel industrieë gebruik word, produseer dikwels produkstrome wat ongereageerde n-alkane bevat. Hierdie wasmiddelreeks alkohole word wyd in verskeie industrieë gebruik. Die suiwerheid van die 1-alkohole is dus noodsaaklik. Dit noodsaak doeltreffende na-produksie skeiding van die 1-alkohole en n-alkane. As gevolg van soortgelyke kook- en smeltpunte is tradisionele skeidingsprosesse ondoeltreffend, en dus word gevorderde skeidingstegnieke vereis. Verskeie studies het getoon dat superkritiese vloeistoffraksionering (SFF) 'n lewensvatbare alternatief is. Die effektiewe ontwerp van SFF-prosesse vereis betroubare fase-ewewigsdata en kennis van toepaslike termodinamiese modelle wat die fasegedrag akkuraat kan korreleer of voorspel. Hierdie studie het ten doel gehad om die binêre dampvloeistof-ewewig (VLE) data vir 1-alkohol + n-alkaanstelsels te ondersoek, waarin die n-alkaan 3-, 2- en 1-koolstof groter as die 1-alkohol is. Hierdie doelwit is bereik deur eksperimenteel vyftien nuwe binêre VLE-datastelle by sub-atmosferiese druk (40 kPa) te meet, die neigings wat vir hierdie stelsels waargeneem is te interpreteer en die nuut gemete data in Aspen Plus® te modelleer. Data is gemeet vir 1-alkohole wat wissel tussen C5 – C10 en n-alkane wat wissel tussen C8 – C13 deur middel van 'n dinamiese-analitiese tegniek. Hierdie data was gemeet om 'n vorige studie aan te vul wat data gemeet het vir 1-alkohole wat wissel tussen C5 – C10 en n-alkane wat wissel tussen C9 – C14. Die betroubaarheid en akkuraatheid van die nuut gemete data is bevestig deur die metodologie te verifieër en daarom is data vir goed gedokumenteerde literatuur datastelle gemeet en vergelyk. Daarbenewens is die termodinamiese konsistensie van die data geëvalueer deur middel van die L-W, McDermott-Ellis en Fredenslund toetse. Die nuut gemete data het sterk positiewe afwykings vanaf ideale gedrag getoon, terwyl daar in na-kokende kombinasies temperatuur-minimum azeotrope voorgekom het. Verskeie konsekwente neigings is vir die data waargeneem. Die afwyking van idealiteit het afgeneem, en die azeotropiese komposisie samestelling het in die rigting van die 1-alkoholryke deel van die komposisionele spektrum geskuif, soos die koolstofkettinglengte van die suiwer komponente binne elke groep data toegeneem het. Tussen groepe sisteme het die afwyking van idealiteit toegeneem. Die azeotropiese komposisie samestelling het ook toegeneem in die rigting van die 1-alkohol ryk streek, soos wat die verskil tussen die koolstofkettinglengtes van een tot vier koolstofstowwe toegeneem het. Die data is gemodelleer in Aspen Plus® deur gebruik te maak van die nie-ewekansige tweevloeistof (NRTL) model, die voorspellende Soave Redlich-Kwong (PSRK) + UNIFAC en PSRK + NRTL modelle. Die NRTL-model het beter as die ander modelle gevaar en die data baie goed gekorreleer. Die PSRK + UNIFAC-model het laer homoloog kombinasies redelik voorspel, afhangende van die akkuraatheid van die Mathias-Copeman parameters, maar kon nie hoër homoloog kombinasies akkuraat voorspel nie. Die PSRK + NRTL-model het die voorspellings van die PSRK + UNIFAC-model verbeter, deur gepasde NRTL-binêre interaksieparameters in te sluit. Masters 2022-03-09T08:41:16Z 2022-04-29T09:38:51Z 2022-03-09T08:41:16Z 2022-04-29T09:38:51Z 2022-04 Thesis http://hdl.handle.net/10019.1/124877 en_ZA Stellenbosch University xiv, 300 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Thermodynamics Low-pressure Vapour-liquid equilibrium Manufacturing processes du Plessis, Susanna Hendrina The measurement and modelling of low-pressure phase equilibrium data for 1-alcohols + n-alkanes |
| title | The measurement and modelling of low-pressure phase equilibrium data for 1-alcohols + n-alkanes |
| title_full | The measurement and modelling of low-pressure phase equilibrium data for 1-alcohols + n-alkanes |
| title_fullStr | The measurement and modelling of low-pressure phase equilibrium data for 1-alcohols + n-alkanes |
| title_full_unstemmed | The measurement and modelling of low-pressure phase equilibrium data for 1-alcohols + n-alkanes |
| title_short | The measurement and modelling of low-pressure phase equilibrium data for 1-alcohols + n-alkanes |
| title_sort | measurement and modelling of low pressure phase equilibrium data for 1 alcohols n alkanes |
| topic | Thermodynamics Low-pressure Vapour-liquid equilibrium Manufacturing processes |
| url | http://hdl.handle.net/10019.1/124877 |
| work_keys_str_mv | AT duplessissusannahendrina themeasurementandmodellingoflowpressurephaseequilibriumdatafor1alcoholsnalkanes AT duplessissusannahendrina measurementandmodellingoflowpressurephaseequilibriumdatafor1alcoholsnalkanes |