Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Phase equilibria measurements and modelling of {water + cyclohexane + ethanol + 1-propanol} system
Thesis (MEng)--Stellenbosch University, 2023.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2023
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613876474871808 |
|---|---|
| access_status_str | Open Access |
| author | Erasmus, Amanda Stephanie |
| author2 | Schwarz, Cara Elsbeth |
| author_browse | Erasmus, Amanda Stephanie Schwarz, Cara Elsbeth |
| author_facet | Schwarz, Cara Elsbeth Erasmus, Amanda Stephanie |
| author_sort | Erasmus, Amanda Stephanie |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/129067 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:43:06.958Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/129067 Phase equilibria measurements and modelling of {water + cyclohexane + ethanol + 1-propanol} system Erasmus, Amanda Stephanie Schwarz, Cara Elsbeth De Klerk, Danielle Lee Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Process Engineering. Liquid-liquid equilibrium Thermodynamics -- Mathematical models Cyclohexane Ethanol Azeotropic distillation Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: The industry has a growing demand for short-chain anhydrous alcohols as fuel additives to increase the octane rating and reduce carbon monoxide emissions. These alcohols are often found in dilute aqueous streams from processes like Fischer-Tropsch reaction water and bio-alcohol production. Due to the azeotropic nature of water and alcohols, enhanced separation techniques like heterogeneous azeotropic distillation (HAD) are necessary. Reliable thermodynamic models and/or experimental data are required to design HAD separation sequences. This work aimed to investigate the liquid-liquid equilibrium (LLE), vapour-liquid equilibrium (VLE), and vapour-liquid-liquid equilibrium (VLLE) of a quaternary system: {water + cyclohexane + ethanol + 1-propanol} at atmospheric pressure. Data were measured at four ethanol:1-propanol ratios. The capability of the Non-Random Two-Liquid (NRTL) and the Universal Functional Activity Coefficient (UNIFAC) thermodynamic models in describing the quaternary LLE phase behaviour was assessed. LLE measurements were conducted using shake flasks in a temperature-controlled (298.2 K to 328.2 K) water bath, while VLE and VLLE measurements were performed with a dynamic Gillespie still equipped with an ultrasonic homogenizer. The data underwent validation and thermodynamic consistency tests, confirming its reliability. The LLE data revealed that the presence of a second alcohol affected the phase behaviour of the respective ternary systems. The total alcohol exhibited evolutionary behaviour between the constituent ternary systems in the size of the heterogeneous region and the distribution between the aqueous and organic phases. Less polar 1-propanol molecules increased the recovery of more polar and smaller ethanol molecules into the organic phase, while the smaller, more polar ethanol molecules increased the recovery of 1-propanol molecules into the aqueous phase. These findings indicate significant interactions between ethanol and 1-propanol in the respective ternary systems. The temperature dependence observed in the quaternary system aligned with expectations from the ternary systems. The mutual solubility between the aqueous and organic phases and the total alcohol recovered to the organic phase increased with an increase in temperature. Both VLE and VLLE data demonstrated the absence of a quaternary azeotrope, with all vapour phases in the VLE data tending toward the {water + cyclohexane + ethanol} ternary heterogeneous azeotrope. The higher the proportion of 1-propanol within the total alcohol in the quaternary system the greater the relative volatility between water and the total alcohol. This increased relative volatility facilitates easier separation in HAD. The VLLE data showed similar alcohol behaviour to the LLE data. The ability of the UNIFAC, UNIQUAC and NRTL thermodynamic models to describe LLE phase behaviour was assessed. Different sets of model parameters for the NRTL model were assessed, which included default Aspen Plus V11 parameters, literature-published parameters, and correlation with ternary LLE data in this work. The NRTL model using BIPs correlated to ternary LLE exhibited the best qualitative and quantitative performance for both {water + cyclohexane + alcohol} ternary systems. These results highlight the need for semi-empirical models like NRTL over the predictive group contribution UNIFAC model. Suggestions for future research include refining the NRTL model parameters and exploring different combinations of short-chain alcohols and entrainers to deepen the understanding of alcohol-alcohol and entrainer-alcohol interactions, ultimately improving the design of HAD separation processes. AFRIKAANSE OPSOMMING: Die industrie het ’n groeiende aanvraag vir kortketting anhidriese alkohole as brandstofbymiddels om die oktaanwaardering te verhoog en koolstofmonoksiedemissies te verlaag. Hierdie alkohole word gereeld gevind in verdunde waterige strome van prosesse soos Fischer-Tropsch-reaksie-water en bioalkoholproduksie. As gevolg van die aseotropiese natuur van water en alkohole, is verbeterde tegnieke soos heterogene aseotropiese distillasie (HAD) nodig. Betroubare termodinamiese modelle en/of eksperimentele data word benodig om HAD-skeidingreekse te ontwerp. Hierdie werk het beoog om die vloeistof-vloeistof-ekwilibrium (LLE), damp-damp-ekwilibrium (VLE), en damp-vloeistof-vloeistof-ekwilibrium (VLLE) van ’n kwarternêre sisteem te ondersoek: {water + sikloheksaan + etanol + 1-propanol} by atmosferiese druk. Data is gemeet by vier etanol:1-propanolverhoudings. Die vermoë van die Nie-Lukrake Twee-Vloeistof (NRTL) en die Universele Funksionele Aktiwiteitskoëffisiënt (UNIFAC) termodinamiese modelle wat die kwartenêre LLE-fase beskryf, is geassesseer. LLE-mates is uitgevoer deur skudflesse in ’n temperatuur-beheerde (298.2 K tot 328.2 K) waterbad te gebruik, terwyl VLE- en VLLE-mates uitgevoer is met ’n dinamiese Gillespie-distelleerketel toegepas met ’n ultraklank homogenisator. Die data het validasie ondergaan asook termodinamiese konswekentheidstoetse, wat sy betroubaarheid bevestig het. Die LLE-data het onthul dat die teenwoordigheid van ’n tweede alkohol die fasegedrag van die onderskeidelike ternêre sisteme beïnvloed het. Die totale alkohol vertoon evolusionêre gedrag tussen die bestanddeel ternêre sisteme in die grootte van die heterogene streek en die verspreiding tussen die waterige en organiese fases. Minder polêre 1-propanolmolekules het die herwinning van meer polêre en kleiner etanolmolekules in die organiese fase verhoog, terwyl die kleiner, meer polêre etanolmolekules die herwinning van 1-propanolmolekules in die waterige fase verhoog het. Hierdie bevindinge het die beduidende interaksies tussen etanol en 1-propanol in die onderskeidelike ternêre sisteme aangedui. Die temperatuurafhanklikheid waargeneem in die kwartenêre sisteem het belyn met verwagtinge van die ternêre sisteme. Die gemeenskaplike oplosbaarheid tussen die waterige en organiese fases en die totale alkohole herwin tot die organiese fase het verhoog met ’n verhoging met temperatuur. Beide VLE- en VLLE-data het die afwesigheid van ’n kwartenêre aseotroop gedemonstreer, met alle dampfases in die VLE-data wat na die {water + sikloheksaan + etanol}-ternêre heterogene aseotroop leun. Hoe hoër die proporsie van 1-propanol binne die totale alkohol in die kwartenêre sisteem, hoe groter die relatiewe vlugtigheid tussen water en die totale alkohol. Hierdie verhoogde relatiewe vlugtigheid fasiliteer makliker skeiding in HAD. Die VLLE-data toon soortgelyke alkoholgedrag tot die LLE-data. Die vermoë van die UNIFAC- en NRTL-termodinamiese modelle om LLE-fasegedrag te beskryf, is geassesseer. Verskillende stelle van modelparameters vir die NRTL-model is geassesseer, wat ingesluit het verstek Aspen Plus V11-parameters, literatuur-gepubliseerde parameters, en korrelasie met ternêre LLE-data in hierdie werk. Die NRTL-model wat korrelerende BIPs gebruik het, het die beste kwalitatiewelike en kwantitatiewelike doeltreffendheid vir beide {water + sikloheksaan + alkohol}- ternêre sisteme vertoon. Hierdie resultate beklemtoon die behoefte aan semi-empiriese modelle soos NRTL oor die voorspellende groepbydra UNIFAC-model. Voorstelle vir toekomende navorsing sluit in verfyning van NRTL-modelparameters en ontdekking van verskillende kombinasies van kortkettingalkohole en meesleurers om ons verstaan van alkoholalkohol- en meesleurer-alkohol-interaksies te verdiep, wat uiteindelik die ontwerp vir HADskeidingprosesse sal verbeter. Masters 2023-11-29T09:34:38Z 2024-01-08T21:12:20Z 2023-11-29T09:34:38Z 2024-01-08T21:12:20Z 2023-12 Thesis https://scholar.sun.ac.za/handle/10019.1/129067 en_ZA en_ZA Stellenbosch University application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Liquid-liquid equilibrium Thermodynamics -- Mathematical models Cyclohexane Ethanol Azeotropic distillation Erasmus, Amanda Stephanie Phase equilibria measurements and modelling of {water + cyclohexane + ethanol + 1-propanol} system |
| title | Phase equilibria measurements and modelling of {water + cyclohexane + ethanol + 1-propanol} system |
| title_full | Phase equilibria measurements and modelling of {water + cyclohexane + ethanol + 1-propanol} system |
| title_fullStr | Phase equilibria measurements and modelling of {water + cyclohexane + ethanol + 1-propanol} system |
| title_full_unstemmed | Phase equilibria measurements and modelling of {water + cyclohexane + ethanol + 1-propanol} system |
| title_short | Phase equilibria measurements and modelling of {water + cyclohexane + ethanol + 1-propanol} system |
| title_sort | phase equilibria measurements and modelling of water cyclohexane ethanol 1 propanol system |
| topic | Liquid-liquid equilibrium Thermodynamics -- Mathematical models Cyclohexane Ethanol Azeotropic distillation |
| url | https://scholar.sun.ac.za/handle/10019.1/129067 |
| work_keys_str_mv | AT erasmusamandastephanie phaseequilibriameasurementsandmodellingofwatercyclohexaneethanol1propanolsystem |