BINARY VAPOUR-LIQUID EQUILIBRIUM FOR SYSTEMS OF INDUSTRIAL IMPORTANCE

Transcription

1 BINARY VAPOUR-LIQUID EQUILIBRIUM FOR SYSTEMS OF INDUSTRIAL IMPORTANCE By Funmlola Elzabeth Avoseh B.Sc. Chemcal and Polymer Engneerng Lagos State Unversty, Lagos state, Ngera. 2015

2 PREFACE The work presented n ths dssertaton enttled Bnary Vapour-Lqud Equlbrum for Systems of Industral Importance was carred out n the School of Engneerng at the Unversty of KwaZulu-Natal, Howard College Campus, Durban, from Aprl 2013 to July 2014 under the supervson of Professor D. Ramjugernath and Doctor C. Narasgadu and has been submtted n fulfllment of the academc requrements for the degree of Master of Scence n Chemcal Engneerng at the School of Chemcal Engneerng, Unversty of KwaZulu-Natal, Durban, South Afrca.

3 I, Funmlola Elzabeth Avoseh, declare that: DECLARATION. The research reported n ths research proposal, except where otherwse ndcated, s my orgnal work.. Ths research proposal has not been submtted for any degree or examnaton at any other unversty.. Ths research proposal does not contan other persons data, pctures, graphs or other nformaton, unless specfcally acknowledged as beng sourced from other persons. v. Ths research proposal does not contan other persons wrtng, unless specfcally acknowledged as beng sourced from other researchers. Where other wrtten sources have been quoted, then: v (a) ther words have been re-wrtten but the general nformaton attrbuted to them has been referenced; (b) where ther exact words have been used, ther wrtng has been placed nsde quotaton marks, and referenced. Ths dssertaton does not contan text, graphcs or tables coped and pasted from the Internet, unless specfcally acknowledged, and the source beng detaled n the dssertaton and n the References sectons. Avoseh F.E. Date As the canddate s supervsor, I, Prof. D. Ramjugernath approved ths dssertaton for submsson. Prof. D. Ramjugernath As the canddate s co-supervsor, I, Dr. C. Narasgadu approved ths dssertaton for submsson. Dr. C. Narasgadu

4 ACKNOWLEDGEMENT I would lke to take ths opportunty to gve my sncere acknowledgement to the followng people who have made sgnfcant contrbuton to ths work: My supervsors Professor D. Ramjugernath and Doctor C. Narasgadu for ther mmense support and gudance n the course of ths work. Thanks so much and I really apprecate All my colleagues n the thermodynamc research unt and most especally, Kank, Welcome, Thokozan, Alsha, Inbanathan, Svannah, Mark and Khald for ther assstance anytme and also to Ayanda who was never tred of gvng hs techncal assstance at my beck and call. You guys rock. The Natonal Research Foundaton (NRF) of South Afrca for fnancal support. The Deeper Lfe Campus Fellowshp (UFH and Howard Campus) members for ther prayers and encouragement I would lke to apprecate Dr Samuel Ayodele Iwarere and famly, thanks a lot for the great assstance and gudance durng my research work. Dr & Prof. (Mrs) O. Oyedej for your unquantfable counsel and support. And lastly to my husband, my love and my lfe partner, Avoseh Opeyem Nudewhenu. I apprecate your support, understandng and encouragement. Thanks for standng by me through thck and thn. I love you and wll always do. Lastly, I would lke to acknowledge and thank the one who deserves all the glory n my lfe, the Almghty God, my Maker, my Savor, my Redeemer Jesus Chrst and the Lord of my lfe. Wthout Hm ths would not have been possble for me. Forever wll I serve you Lord! I am grateful to You. v

5 ABSTRACT Most ndustral chemcal engneerng separaton processes such as dstllaton, extracton, absorpton and adsorpton rely absolutely on accurate phase equlbrum data for effectve desgn, optmzaton and smulaton. Carbonyls and alcohols are known to be of mportant use n the petrochemcal ndustres. Ketones alongsde wth alcohols and carboxylc acds are found both n the product stream and waste stream of the Fscher-Tropsch process. 4-methyl- 2-pentanone forms parts of these by-products and t s used n a number of ndustral applcatons. It s generally used as solvent, as chemcal ntermedate n the producton of pants, rubber products, chemcals, resns and drugs to menton a few, due to ts low solublty n water; t s used for lqud-lqud extracton. Ths work focuses on measurement of new vapour-lqud equlbrum (VLE) data for bnary mxtures of : 1-Propanol (1) + 4- methyl-2-pentanone (2) (at K, K, and K), 2-propanol (1) + 4-methyl-2- pentanone (2) (at K, K, and K) and 2-pentanone (1) + 2-methylpropan- 1-ol (2) (at K, K, and K). A modfed (Bhownath, 2008) low pressure dynamc VLE glass recrculatng stll orgnally desgned by Raal (Raal & Mühlbauer, 1998) was used for the measurements. Ths work also presents the nfnte dluton actvty coeffcents and the excess thermodynamc propertes (.e. molar excess Gbbs energy G E, heat of mxng H E, and excess entropy S E ). These propertes were derved from the measured sothermal VLE data. A hghly non-deal system comprsed of cyclohexane + ethanol was chosen as a test system and was used to verfy the reproducblty and repeatablty of the apparatus. The test system had been measured n our laboratory (Joseph, 2001) and the data were found to agree excellently wth those of Morachevsky and Zharov (1963) and were reported to be thermodynamcally consstent accordng to Gmehlng and Onken (1977). The results for the test system measured n ths work were n excellent agreement wth lterature. Thus, there was confdence n the new data measured snce the apparatus and the operatng procedures used for the test system were able to gve accurate results. The vapour pressures measured n ths study were also n good agreement wth lterature. The temperature, pressure and composton measurng devces were well calbrated and the uncertanty acqured for each s ncluded. v

6 The uncertanty n the pressure measurement was estmated to be ± 0.02 kpa and controlled wthn 0.01 kpa. The uncertanty n the temperature measurement was estmated to be ± 0.06 K (Type B uncertanty, NIST) and was controlled wthn 0.04 K durng manual operaton. The uncertanty n the composton measurement was estmated as ± The 1-propanol (1) + methyl sobutyl ketone (2) system was found to exhbt a mnmum bolng azeotrope at K. The gamma-ph (γ-φ) or combned method was used for the regresson of the measured VLE data. Three actvty coeffcent models were nvestgated to account for the lqud phase devaton of the mxture from dealty: NRTL (Renon and Prausntz, 1968), Wlson (1964) and the UNIQUAC (Abrams and Prausntz, 1975) models. Two equaton of state models were used to account for the vapour phase non- dealty: the vral EoS wth the Hayden O Connell (Hayden & Connell, 1973) correlaton for the calculaton of the second vral coeffcent, and the Nothnagel (Nothnagel, Abrams, & Prausntz, 1973) formulaton. The maxmum lkelhood regresson technque was used to determne the regressed parameters of the actvty coeffcent models. These models were found to ft the measured data well. The measured VLE data passed the pont test of Van Ness(et al., 1973) and the drect test (Van Ness, 1995). v

7 TABLE OF CONTENTS Contents PREFACE... DECLARATION... ACKNOWLEDGEMENT... v ABSTRACT... v TABLE OF CONTENTS... v LIST OF FIGURES... x LIST OF TABLES... xx NOMENCLATURE... xxv... 1 INTRODUCTION REVIEW OF SOME EXPERIMENTAL METHODS FOR VLE MAESUREMENT Classes of expermental VLE equpment Statc Method Dew and Bubble Pont Method Dynamc Method Features of Recrculatng Stll The Gllepse Desgn Modfcatons to the Gllespe Stll The Yerazuns (1964) Stll Desgn The Malanowsk Stll Desgn (1982) Low Pressure VLE stll of Raal (Raal and Mühlbauer, 1998) The VLE stll of Joseph (Joseph, 2001) The modfed VLE stll of Ndlovu (Ndlovu, 2005) The modfed VLE stll of Rnay Bhownath (Bhownath, 2008) v

8 THEORETICAL ASPECTS OF VAPOUR-LIQUID EQUILIBRIUM INTRODUCTION Fugacty coeffcents from the vral equaton of state Hayden-O Connell second vral equaton of state The second vral correlaton of Nothnagel et al. (1973) The Ptzer-Curl correlaton for the second vral coeffcent Actvty and actvty coeffcent The Wlson s equaton The NRTL (Non-Random-Two-Lqud) model The UNIQUAC (Abrams and Prausntz, 1975) model Low pressure VLE data reducton The combned method (γ-φ) for VLE data regresson Thermodynamc consstency testng Pont Test The Drect Test Infnte dluton actvty coeffcent Excess Thermodynamc Propertes EQUIPMENT AND EXPERIMENTAL PROCEDURE Equpment descrpton The dynamc VLE recrculatng stll Pressure measurement and control Temperature measurement and control Samplng and composton analyss Expermental procedure Preparaton of the VLE stll v

9 4.2.2 Temperature, pressure and GC calbraton Refractometer operaton Operatng procedures Isobarc operaton Isothermal operaton Plateau regon EXPERIMENTAL RESULTS Chemcal Purty Uncertanty measurement Vapour pressures Operatng condtons for the Shmadzu 2014 gas chromatograph Bnary vapour-lqud equlbrum measurements Cyclohexane (1) + ethanol system (2) propanol (1) + 4-methyl-2-pentanone (2) system Propanol (1) + 4-methyl-2-pentanone (2) system pentanone (1) + 2-methylpropan-1-ol (2) system DATA ANALYSIS AND DISCUSSION Vapour pressure data regresson Refractometer calbraton for the test system Modellng results for the cyclohexane (1) + ethanol (2) system at K Modellng results for the cyclohexane (1) + ethanol (2) system at 40 kpa Gas chromatograph calbraton for the new systems VLE data regresson Modellng results for the 1-propanol (1) + 4-methyl-2-pentanone (2) system Modellng results for the 2-propanol (1) + 4-methyl-2-pentanone (2) system x

10 6.4.3 Modellng results obtaned for the 2-pentanone (1) + methylpropan-1-ol system Thermodynamc consstency testng results obtaned for the systems measured Consstency results for the 1-propanol (1) + methyl sobutyl ketone (2) system Consstency results for the 2-propanol (1) + 4-methyl-2-pentanone (2) system Consstency results for the 2-pentanone (1) + 2-methyl propan-1-ol (2) system Expermental nfnte dluton actvty coeffcent Excess Thermodynamc Propertes CONCLUSION RECOMMENDATION REFERENCES (Regressed Bnary VLE Data) (Infnte Dluton Actvty Coeffcent) (Excess Thermodynamc Propertes) x

11 LIST OF FIGURES Fgure 2-1: Schematc descrpton of some VLE methods (Raal & Mühlbauer, 1994)... 4 Fgure 2-2: The general prncples of a statc VLE equpment (Uus-kyyny, 2004)... 5 Fgure 2-3:The prncple of the dew and bubble pont method (Uus-kyyny, 2004)... 6 Fgure 2-4: Orgnal Othmer dynamc VLE stll taken from Raal and Mühlbauer (1998)... 8 Fgure 2-5: Schematc of the Orgnal Gllespe stll (Gllepse, 1946) Fgure 2-6: A typcal Yerazuns apparatus (Yerazuns et al., 1964) Fgure 2-7: The Malanowsk (Malanowsk, 1982) stll desgn Fgure 2-8: Block dagram of the apparatus of Joseph taken from (Bhownath, 2008) Fgure 2-9: The VLE stll of Ndlovu (2005) taken from (Bhownath, 2008) Fgure 3-1: Types of bnary T-x-y, P-x-y and x-y phase equlbrum curves: (a) ntermedatebolng systems; (b) systems dsplayng a mnmum bolng azeotrope; (c ) systems dsplayng a maxmum bolng azeotrope (Raal and Mühlbauer, 1998) Fgure 3-2: Block dagram for the bubble pont pressure calculaton. (Smth et al., 2004) Fgure 3-3: Block dagram for the bubble pont temperature calculaton. (Smth et al., 2004) Fgure 4-1: Modfed VLE apparatus of Bhownath (2008) Fgure 4-2: Temperature calbraton plot for the Pt-100 temperature sensor used n the VLE stll Fgure 4-3: Pressure transmtter calbraton plot for the VLE stll Fgure 4-4: Flow dagram to show the steps taken to measure sobarc VLE data usng a low pressure dynamc VLE recrculatng stll Fgure 4-5: Flow dagram to show the steps taken to measure sothermal VLE data usng a low pressure dynamc VLE recrculatng stll Fgure 4-6: Temperature vs energy nput curve showng the plateau regon for a well behaved system (Pllay, 2009) Fgure 5-1: Refractometer calbraton plot for the cyclohexane (1) + ethanol (2) system (ethanol dlute regon) at K Fgure 5-2: Refractometer calbraton plot for the cyclohexane (1) + ethanol (2) system (cyclohexane dlute regon) at K Fgure 5-3: T-x1-y1 plot for cyclohexane (1) + ethanol (2) system at 40 kpa; ( ) ( ), Joseph (2001); ( ), ths work x

12 Fgure 5-4: x1-y1 plot for cyclohexane (1) + ethanol (2) system at 40 kpa; ( ) Joseph (2001); ( ), ths work Fgure 5-5: P-x1-y1 plot for cyclohexane (1) + ethanol (2) system at K; ( ), Joseph (2001); ( ), ths work Fgure 5-6: x1-y1 plot for cyclohexane (1) + ethanol (2) system at K; ( ) Joseph (2001); ( ), ths work Fgure 5-7: GC calbraton plot for the 1-propanol (1) + 4-methyl-2-pentanone (2) system (1- propanol dlute regon) Fgure 5-8: GC calbraton plot for 1-propanol (1) + 4-methyl-2-pentanone (2) system (4- Methyl-2-pentanone dlute regon) Fgure 5-9: P-x1-y1 plot for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K.; ( ), P-x1; ( ), P-y Fgure 5-10: x1-y1 plot for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K Fgure 5-11: P-x1-y1 plot for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K.; ( ), P-x1; ( ), P-y Fgure 5-12: x1-y1 plot for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K Fgure 5-13: P-x1-y1 plot for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K.; ( ), P-x1; ( ), P-y Fgure 5-14: x1-y1 plot for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K Fgure 5-15: GC detector calbraton plot for the 2-propanol (1) + 4-methyl-2-pentanone (2) system (2-propanol dlute regon) Fgure 5-16: GC detector calbraton plot for the 2-propanol (1) + 4-methyl-2-pentanone (2) system (4-methyl-2-pentanone dlute regon) Fgure 5-17: P-x1-y1 plot for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K; ( ), P-x1; ( ), P-y Fgure 5-18: x1-y1 plot for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K Fgure 5-19: P-x1-y1 plot for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K; ( ), P-x1; ( ), P-y Fgure 5-20: x1-y1 plot for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K x

13 Fgure 5-21: P-x1-y1 plot for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K; ( ), P-x1; ( ), P-y Fgure 5-22: x1-y1 plot for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K Fgure 5-23: GC detector calbraton plot for the methyl propyl ketone (1) + 2-methylpropan- 1-ol (2) system (2-pentanone dlute regon) Fgure 5-24: GC detector calbraton plot for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system (2-methylpropan-1-ol dlute regon) Fgure 5-25: P-x1-y1 plot for the 2-pentanone (1) + 2-methylproan-1-ol (2) system at K.; ( ), P-x1; ( ), P-y Fgure 5-26: x1-y1 plot for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K Fgure 5-27: P-x1-y1 plot for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K.; ( ), P-x1; ( ), P-y Fgure 5-28: x1-y1 plot for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K Fgure 5-29: P-x1-y1 plot for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K.; ( ), P-x1; ( ), P-y Fgure 5-30: x1-y1 plot for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K Fgure 6-1: Ft of the NRTL-HOC model combnaton to the x-y plot of the cyclohexane (1) + ethanol (2) system at K Fgure 6-2: Ft of the NRTL-HOC model combnaton to the P-x-y plot of the cyclohexane (1) + ethanol (2) system at K Fgure 6-3: Comparson of the expermental actvty coeffcents and those calculated from the NRTL-HOC model combnaton for the cyclohexane (1) + ethanol (2) system at K. ( ) expermental ln γ1, ( ) expermental ln γ2, ( ) NRTL-HOC model combnaton Fgure 6-4: Ft of the NRTL-HOC and WILSON-HOC model combnatons to the x-y plot of the cyclohexane (1) + ethanol (2) system at 40 kpa. ( ) ths work, ( ) NRTL-HOC, (- - -) WILSON-HOC Fgure 6-5: Ft of the NRTL-HOC and WILSON-HOC model combnatons to the T-x-y plot of the cyclohexane (1) + ethanol (2) system at 40 kpa. ( ) P-x1, ( ) P-y1, ( ) NRTL-HOC, (- - -) WILSON-HOC x

14 Fgure 6-6: Comparson of the expermental actvty coeffcents and those calculated from the NRTL-HOC and WILSON-HOC model combnatons for the cyclohexane (1) + ethanol (2) system at 40 kpa. ( ) expermental ln γ1, ( ) expermental ln γ2, ( ) NRTL-HOC, (- - -) WILSON-HOC Fgure 6-7: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the p-x-y plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-8: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the x-y plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-9: Pont test (varyng EOS) y1 for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K: ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-10: Drect test (varyng EOS): δln(γ1/γ2) for the 1-propanol (1) + 4-methyl-2- pentanone (2) system at K : ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-11: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the P-x-y plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-12: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the x-y plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-13: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the P-x-y plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-14: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the x-y plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-15: Comparson between the expermentally determned lqud-phase actvty coeffcents and those calculated from the NRTL model for 1-propanol (1) + 4-methyl-2- pentanone (2) system at K, K and K K ( ), K ( ) and K (- - -) for NRTL-HOC model combnaton; K ( ), K ( ) and K (Δ), for expermental γ1; K ( ), K ( ) and K ( ), for expermental γ Fgure 6-16: Temperature dependence of the NRTL-HOC model combnaton parameters for 1-propanol (1) + 4-methyl-2-pentanone (2) system. ( ), g21-g12; ( ) g12-g xv

15 Fgure 6-17: Ft of the NRTL-HOC and the NRTL-NTH models to the P-x-y plot of the 2- propanol (1) + methyl sobutyl (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-18: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the x-y plot of the 2-propanol (1) + methyl sobutyl ketone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-19: Pont test (varyng EOS): y1 for the 2-propanol (1) + methyl sobutyl ketone (2) system at K: ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-20: Drect test (varyng EOS): δln(γ1/γ2) for the 2-propanol (1) + 4-methyl-2- pentanone (2) system at K: ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-21: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the p-x-y plot of the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-22: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the x-y plot of the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-23: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the p-x-y plot of the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-24: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the x-y plot of the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-25: Comparson between the expermentally determned lqud-phase actvty coeffcents and those calculated from the NRTL-HOC model combnaton for 2-propanol (1) + 4-methyl-2-pentanone (2) system at K, K and K K ( ), K ( ) and K (- - -) for NRTL-HOC model combnaton; K ( ), K ( ) and K (Δ), for expermental γ1; K ( ), K ( ) and K ( ), for expermental γ Fgure 6-26: Temperature dependence of the NRTL-HOC model combnaton parameters for 2-propanol (1) + 4-methyl-2-pentanone (2) system. ( ) g21-g12; ( ) g12-g Fgure 6-27: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the P-x-y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH xv

16 Fgure 6-28: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the x-y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-29: Pont test (varyng EOS): y1 for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K: ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-30: Drect test (varyng EOS): δln(γ1/γ2) for the 2-pentanone (1) + 2-methylpropan- 1-ol (2) system at K: ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-31: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the P-x-y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-32: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the x-y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-33: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the P-x-y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-34: Ft of the NRTL-HOC and NRTL-NTH model combnatons to the x-y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( ) NRTL-NTH Fgure 6-35: Comparson between the expermentally determned lqud-phase actvty coeffcents and those calculated from the NRTL-HOC model combnaton for 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K, K and K. ( ) K, ( ) K and (- - -) K for NRTL-HOC model combnaton; ( ) K, ( ) K and (Δ) K for expermental γ1; ( ) K, ( ) and ( ) K for expermental γ Fgure 6-36: Temperature dependence of the NRTL-HOC model combnaton parameters for 2-pentanone (1) + 2-methylpropan-1-ol (2) system. (g12 g22) ( ), (g21 g11) ( ) Fgure 6-37: Temperature dependence of the WILSON-HOC model combnaton parameters for 2-pentanone (1) + 2-methylpropan-1-ol (2) system. (λ12 λ22) ( ), (λ21 λ11) ( ) Fgure 6-38: Plot of (x1x2/pd) vs x1 as x1 1 for 1-propanol (1) + 4-methyl-2-pentanone (2) system at K Fgure 6-39: Plot of (x1x2/ PD) vs x1 as x1 0 for 1-propanol (1) + 4-methyl-2-pentanone (2) system at K xv

17 Fgure 6-40: Plot used for the determnaton of the molar excess enthalpy values for the 1- propanol (1) + 4-methyl-2-pentanone (2) system at K, K and K. ( ), 0.1, ( ), 0.2, ( ), 0.3 and ( ), Fgure 6-41: Excess thermodynamc propertes (H E, G E and TS E ) for 1-propanol (1) + 4- methyl-2-pentanone (2) system at K Fgure 6-42: Excess thermodynamc propertes (H E, G E and TS E ) for 1-propanol (1) + 4- methyl-2-pentanone (2) system at K Fgure 6-43: Excess thermodynamc propertes (H E, G E and TS E ) for 1-propanol (1) + 4- methyl-2-pentanone (2) system at K APPENDIX A Fgure A- 1: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the P-xy plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 2: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the x-y plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 3: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the P- x-y plot for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 4: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the x-y plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 5: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the P-xy plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC xv

18 Fgure A- 6: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the x-y plot of the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 7: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the P-xy plot of the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 8: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the x-y plot of the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 9: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the P-xy plot of the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 10: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the x- y plot of the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 11: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the P- x-y plot of the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 12: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the x- y plot of the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 13: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the P- x-y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 14: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the x- y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned xv

19 method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 15: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the P- x-y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 16: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the x- y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 17: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the P- x-y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 18: Ft of the NRTL-HOC, WILSON-HOC and UNIQUAC-HOC models to the x- y plot of the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K for the combned method: ( ) ths work, ( ) NRTL-HOC, ( - - ) WILSON-HOC, (...) UNIQUAC-HOC Fgure A- 19: Pont test (varyng actvty coeffcent model): y1 for the 1-propanol (1) + 4- methyl-2-pentanone (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 20: Drect test (varyng actvty coeffcent model): δln(γ1/γ2) for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 21: Pont test (varyng actvty coeffcent model): y1 for the 1-propanol (1) + 4- methyl-2-pentanone (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 22: Drect test (varyng actvty coeffcent model): δln(γ1/γ2) for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K : ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 23: Pont test (varyng actvty coeffcent model): y1 for the 1-propanol (1) + 4- methyl-2-pentanone (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC xx

20 Fgure A- 24: Drect test (varyng actvty coeffcent model): δln(γ1/γ2) for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K : ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 25: Pont test (varyng actvty coeffcent model): y1 for the 2-propanol (1) + 4- methyl-2-pentanone (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 26: Drect test (varyng actvty coeffcent model): δln(γ1/γ2) for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 27: Pont test (varyng actvty coeffcent model): y1 for the 2-propanol (1) + 4- methyl-2-pentanone (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 28: Drect test (varyng actvty coeffcent model): δln(γ1/γ2) for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 29: Pont test (varyng actvty coeffcent model): y1 for the 2-propanol (1) + 4- methyl-2-pentanone (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 30: Pont test (varyng actvty coeffcent model): y1 for the 2-pentanone (1) + 2- methylpropan-1-ol (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC -HOC Fgure A- 31: Drect test (varyng actvty coeffcent model): δln(γ1/γ2) for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC HOC Fgure A- 32: Pont test (varyng actvty coeffcent model): y1 for the 2-pentanone (1) + 2- methylpropan-1-ol (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC HOC Fgure A- 33: Drect test (varyng actvty coeffcent model): δln(γ1/γ2) for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC HOC Fgure A- 34: Pont test (varyng actvty coeffcent model): y1 for the 2-pentanone (1) + 2- methylpropan-1-ol (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC HOC xx

21 Fgure A- 35: Drect test (varyng actvty coeffcent model): δln(γ1/γ2) for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K: ( ) NRTL-HOC, ( ) WILSON-HOC, ( ) UNIQUAC HOC APPENDIX B Fgure B- 1: Plot of (x1x2/pd) vs x1 as x1 0 for 1-propanol (1) + 4-methyl-2-pentanone (2) at K ( ) and K ( ) Fgure B- 2: Plot of (PD/x1x2) vs x1 as x1 1 for 1-propanol (1) + 4-methyl-2-pentanone (2) at K ( ) and K ( ) Fgure B- 3: Plot of (x1x2/pd) vs x1 as x1 0 for 2-propanol (1) + 4-methyl-2-pentanone (2) at K ( ), K ( ) and K ( ) Fgure B- 4: Plot of (PD/x1x2) vs x1 as x1 1 for 2-propanol (1) + 4-methyl-2-pentanone (2) at K ( ) and K ( ) Fgure B- 5: Plot of (PD/x1x2) vs x1 as x1 0 for 2-pentanone (1) + 2-methylpropan-1-ol (2) at K ( ) and K ( ) Fgure B- 6: Plot of (x1x2/pd) vs x1 as x1 0 for 2-pentanone (1) + 2-methylpropan-1-ol (2) at K Fgure B- 7: Plot of (PD/x1x2) vs x1 as x1 1 for 2-pentanone (1) + 2-methylpropan-1-ol (2) at K ( ), K ( ) and K ( ) APPENDIX C Fgure C- 1: Plot used for the determnaton of the molar excess enthalpy values for 2- propanol (1) + 4-methyl-2-pentanone (2) system at K, K and K. ( ), 0.1, ( ), 0.2, ( ), 0.3 and ( ), Fgure C- 2: Excess thermodynamc propertes (H E, G E and TS E ) for 2-propanol (1) + 4- methyl-2-pentanone (2) system at K xx

22 Fgure C- 3 : Excess thermodynamc propertes (H E, G E and TS E ) for 2-propanol (1) + 4- methyl-2-pentanone (2) system at K Fgure C- 4: Excess thermodynamc propertes (H E, G E and TS E ) for 2-propanol (1) + 4- methyl-2-pentanone (2) system at K Fgure C- 5: Plot used for the determnaton of the molar excess enthalpy values for 2- pentanone (1) + 2-methylpropan-1-ol (2) system at K, K and K. ( ), 0.1, ( ), 0.2, ( ), 0.3 and ( ), Fgure C- 6: Excess thermodynamc propertes (H E, G E and TS E ) for 2-pentanone (1) +2- methylpropan-1-ol (2) system at K Fgure C- 7: Excess thermodynamc propertes (H E, G E and TS E ) for 2-pentanone (1) +2- methylpropan-1-ol (2) system at K Fgure C- 8: Excess thermodynamc propertes (H E, G E and TS E ) for 2-pentanone (1) +2- methylpropan-1-ol (2) system at K xx

23 LIST OF TABLES Table 3-1: The drect test (Van Ness, 1995) consstency table Table 5-1: Chemcal purtes and refractve ndces Table 5-2: Expermental uncertantes for temperature, pressure and composton of the measured VLE bnary systems Table 5-3: Expermental Vapour pressure data for 1-propanol. a Table 5-4: vapour pressure data for 2-methylpropan-1-ol a Table 5-5: vapour pressure data for 2-pentanone a Table 5-6: vapour pressure data for 4-methyl-2-pentanone a Table 5-7: vapour pressure data for 2-propanol a Table 5-8: vapour pressure data for cyclohexane a Table 5-9: vapour pressure data for ethanol a Table 5-10: GC operatng condtons for the 1-propanol (1) + 4-methyl-2-pentanone (2) system Table 5-11: GC operatng condtons for the 2-propanol (1) + 4-methyl-2-pentanone (2) system Table 5-12: GC operatng condtons for the methyl propyl ketone (1) + 2-methylpropan-1-ol (2) system Table 5-13: Vapour-lqud equlbrum data for the cyclohexane (1) + ethanol (2) at 40 kpa a Table 5-14: Vapour-lqud equlbrum data for cyclohexane (1) + ethanol (2) at K. a 75 Table 5-15: Vapour lqud equlbrum data for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K. a Table 5-16: Vapour-lqud equlbrum data for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K. a Table 5-17: Vapour-lqud equlbrum data for the 1-propanol (1) + 4-methyl-2-pentanone (2) system at K. a Table 5-18: Vapour lqud equlbrum data for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K. a Table 5-19: Vapour lqud equlbrum data for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K. a Table 5-20: Vapour lqud equlbrum data for the 2-propanol (1) + 4-methyl-2-pentanone (2) system at K. a xx

24 Table 5-21: Vapour lqud equlbrum data for the methyl propyl ketone (1) + 2- methylpropan-1-ol (2) system at K. a Table 5-22: Vapour lqud equlbrum data for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K Table 5-23: Vapour lqud equlbrum data for the 2-pentanone (1) + 2-methylpropan-1-ol (2) system at K. a Table 6-1: Parameters obtaned for the Antone equaton Table 6-2: modellng results obtaned for the cyclohexane (1) + ethanol (2) system at K Table 6-3: modellng results obtaned for the cyclohexane (1) + ethanol (2) system at 40 kpa Table 6-4: modellng results obtaned for the 1-propanol (1) + 4-methyl-2-pentanone (2) system Table 6-5: Model results obtaned for the 2-propanol (1) + 4-methyl-2-pentanone (2) system Table 6-6: modellng results obtaned for the 2-pentanone (1) + 2-methylpropan-1-ol system Table 6-7: Best model for the new sotherms measured n ths work Table 6-8: Results for the pont and drect test performed for the data set measured for the 1- propanol (1) + 4-methyl-2-pentanone (2) at K, K and K Table 6-9: Results for the pont and drect test performed for the data set measured for the 2- propanol (1) + 4-methyl-2-pentanone (2) at K, K and K Table 6-10: Results for the pont and drect test performed for the data set measured for the 2- pentanone (1) + 2-methylpropan-1-ol at K, K and K Table 6-11: Second vral coeffcents and lqud molar volumes calculated for ths work Table 6-12: comparson of the nfnte dluton actvty coeffcent values obtaned by extrapolaton of the expermental γ wth values calculated usng the Maher and Smth (1979) method and the Wlson (1964) method for the sothermal VLE systems measured Table 6-13: Excess Gbbs energy (G E ) values obtaned for the system 1-propanol (1) + 4- methyl-2-pentanone (2) Table 6-14: Excess enthalpy values (H E ) obtaned for the system 1-propanol (1) + 4-methyl- 2-pentanone (2) Table 6-15: Excess entropy values (TS E ) obtaned for the system 1-propanol (1) + 4-methyl- 2-pentanone (2) xxv

25 Table 6-16: Excess Gbbs energy (G E ) values obtaned for the system 2-propanol (1) + 4- methyl-2-pentanone (2) Table 6-17: Excess enthalpy (H E ) values obtaned for the system 2-propanol (1) + 4-methyl- 2-pentanone (2) Table 6-18: Excess entropy (TS E ) values obtaned for the system 2-propanol (1) + 4-methyl- 2-pentanone (2) Table 6-19: Excess Gbbs energy (G E ) values obtaned for the system 2-pentanone (1) + 2- methylpropan-1-ol (2) Table 6-20: Excess enthalpy (H E ) values obtaned for the system 2-pentanone (1) + 2- methylpropan-1-ol (2) Table 6-21: Excess enthalpy (TS E ) values obtaned for the system 2-pentanone (1) + 2- methylpropan-1-ol (2) xxv

26 NOMENCLATURE Englsh Letter Unts a Actvty of a lqud ( - ) A Constant n the Antone equaton ( - ) aj Constants for temperature dependency of model parameters ( - ) B Constant n the Antone equaton ( - ) B Second vral coeffcent of pure component [cm 3 /mol] bj Constants for temperature dependency of model parameters ( - ) Bj Second vral coeffcent for speces speces j nteracton [cm 3 /mol] C Constant n the Antone equaton ( - ) cj Constants for temperature dependency of model parameters ( - ) dj Constants for temperature dependency of model parameters ( - ) ej Constants for temperature dependency of model parameters ( - ) f Fugacty [kpa] f 0 Fugacty of the pure component n a standard (or reference) state ( - ) f Fugacty n soluton of component [kpa] F Degrees of freedom of the system (Gbbs phase rule) ( - ) fj Constants for temperature dependency for model parameters ( - ) gj-g Parameter n NRTL (1968) model representng nteractons between speces ( - ) G Molar or specfc Gbbs energy [J/mol] G Partal molar Gbbs free energy ( - ) H Molar or specfc Enthalpy [J/mol] K Chemcal equlbrum constant for assocaton equlbra ( - ) xxv

27 l Parameter n the UNIQUAC (1975) model ( - ) n Number of moles of component ( - ) N Number of chemcal speces or components present n a system ( - ) P System pressure [kpa] q Pure component area parameter n the UNIQUAC (1975) model ( - ) Q Energy transferred as heat energy ( - ) r Pure component volume parameter n the UNIQUAC (1975) model ( - ) R Unversal gas constant [J/mol.K] S Molar or specfc entropy [J/mol.K] T System temperature [ 0 C or K] U Molar or specfc nternal energy (J) V Molar or specfc volume [cm 3 /mol] Vm Molar volume [cm 3 /mol] w Normalzng factor ( - ) W Work done on a system (J) x Mole fracton of component n the lqud phase ( - ) y Mole fracton of component n the vapour phase ( - ) z Co-ordnaton number n the UNIQUAC (1975) model ( - ) Z Compressblty factor ( - ) xxv

28 Greek Letters α12 γ δ η θ and θ' Non-randomness parameter n NRTL (1968) model Actvty coeffcent of component Denotes a resdual (e.g. δt) Denotes the resdual for the pont test Solvaton (unlke speces) and assocaton (pure speces) parameters (HOC) Area fractons n UNIQUAC (1975) equaton λ Parameter representng nteractons between speces n the Wlson (1964) model Λj μ π τj ϕ ϕ Φ φ Parameter n Wlson (1964) model Chemcal potental of component Number of phases present n a system (Gbbs phase rule) Parameter n the NRTL (1968) model and UNIQUAC (1975) model Fugacty coeffcent Fugacty coeffcent n soluton Rato of fugacty coeffcents, wth the pontng correcton factor True speces fugacty coeffcent Superscrpts exp E d L Lt Denotes values calculated from expermental data Denotes an excess property Denotes an deal soluton Denotes the lqud phase Refers to lterature data xxv

29 Sat V Denotes a saturated value Denotes the vapour phase Subscrpts 1 Denotes component 1 (the more volatle component n a bnary mxture) 2 Denotes component 2 (the less volatle component n a bnary mxture) avg c rev Denotes an average value Denotes a crtcal property Denotes reversble processes xxx

30 INTRODUCTION In chemcal ndustres, t has been shown that the total cost of separaton s up to 40-70% of the total operatng cost of a plant. Therefore, adequate knowledge of separaton s hghly mportant for the practcng engneer. Dstllaton s consdered as the oldest and most wdely used separaton process n the chemcal and petrochemcal ndustres. Phase equlbrum analyss forms the bass of dstllaton process desgn. Accurate and relable phase equlbrum data (whch ncludes VLE) s essental for the desgn and optmum operaton of dstllaton columns and other separaton processes. Expermental data for several systems are scarce and rarely avalable n the lterature thereby causng dffcultes n desgnng separaton processes for some specfc systems n the ndustres. Most process desgners have been left wth the choce of usng dfferent thermodynamc models for predctng phase behavor of components for systems of nterest. Predctve methods are easy and fast to access but may be unrelable for complex and hghly non-deal systems. Measurement of VLE data though qute expensve and tme consumng has been found to be more relable and accurate than the so-called predctve method. In addton, expermental data have always been used n the understandng of phase change phenomena. Nowadays, expermental data together wth useful thermodynamc models are used to account for the varous aspects of ntermolecular nteractons of mxtures (Prausntz, 1999). The applcatons of some of these models n phase equlbra have been qute successful. Though expermental data measurements could be tme and cost consumng, they stll offer best results due to ther reproducblty and ts consstency. Phase equlbrum data also provdes the thermodynamc knowledge of hghly non-deal systems. nformaton on azeotropc or near azeotropc behavor whch s an example of nondealty helps n the desgn of dstllaton process as ordnary dstllaton process s not sutable for separatng systems that exhbt azeotropes (Narasgadu et al., 2013). There are varous methods avalable for separatng systems that are azeotropc n nature (Seader and Henley, 1998). Ths work was undertaken as a result for need of new VLE data for some ketone + alcohol systems. These chemcals form part of the consttuent components n the ndustral waste streams of petrochemcal plants. In order to desgn and optmze these 1

31 process plants, and also to recover useful by-products, accurate and relable VLE data as well as the relatonshp between varyng temperatures, pressures and compostons of these components s requred. Some prevous sothermal VLE measurements comprsng ketone and alcohols bnary systems have been done n our Thermodynamc Research Unt at the School of Chemcal Engneerng. Jeremy Pllay (Pllay, 2009) measured 2-propanone (1) + 2- butanol (2) at , and K. Prashant Reddy (Reddy, 2006) measured 1- propanol (1) + 2-butanol (2) at , and K. As a result of lack of expermental data n open lterature, ths study focused on expermental measurement and modellng for these systems: 1-propanol (1) + 4-methyl-2-pentanone (2) at K, K and K 2-propanol (1) + 4-methyl-2-pentanone (2) at K, K and K 2-pentanone (1) + 2-methylpropan-1-ol (2) at K, K and K In process smulaton, t s necessary to properly select thermodynamc models as ths serves as a startng pont for an accurate smulaton. In the course of ths work, NRTL,, UNIQUAC, and the Wlson lqud phase actvty coeffcent models were used to account for the nondealty n the lqud phase whle the vapour phase nondealty was accounted for wth the vral equaton of state usng the Hayden O Connell and the Nothnagel second vral coeffcent correlatons. These equatons were found to ft the expermental data well. The new measured VLE data were subjected to rgorous thermodynamc testng to check for the consstency of the measured data. These measurements were undertaken usng a low pressure dynamc recrculatng stll desgned by Raal (Raal and Mühlbauer, 1998) and modfed by Bhownath (Bhownath, 2008). The measured data were regressed usng dfferent thermodynamc models n ASPEN (ASPEN PLUS, 2014 ) n order to obtan the model parameters. In separaton technology, nfnte dluton actvty coeffcents are of great mportance n the producton of hgh purty reagents therefore; for each sothermal VLE system measured n ths work the actvty coeffcents at nfnte dluton were calculated by usng the method of Ells and Jonah (1962) as modfed by Maher and Smth (1979). 2

32 REVIEW OF SOME EXPERIMENTAL METHODS FOR VLE MAESUREMENT A relable and acceptable process desgn requres accurate VLE data measurements and an approprate theory and equatons to descrbe and predct the VLE behavor of components. There are dfferent equpment for VLE measurements because a number of varables and several ranges of condtons are consdered. In other words, the equpment employed wll depend largely on the temperature, pressure and the mxture to be studed. These data are determned expermentally wth equpment that ensures equlbrum between the vapour and lqud phases. there are many revews of expermental procedures and equpment n open lterature such as those of Hala et al.(1967), Abbott (1986), Malanowsk (1982), Raal and Mühlbauer (1994) Dvoskn Natalya (2004). Ths chapter however focuses on some expermental technques for VLE measurements and extends to the proper descrpton of the equpment employed for ths study. 2.1 Classes of expermental VLE equpment. Expermental VLE equpment can be grouped nto two man types based on the type of operaton namely; statc equpment and dynamc (crculaton) equpment. The statc method can also be subdvded nto analytcal (drect samplng method) and synthetc (ndrect samplng) methods dependng on how the compostons of the two coexstng phases are determned. In the statc analytcal method, the phase equlbrum compostons are determned by samplng and analyzng each of the phases. Whle the statc synthetc method nvolves synthetcally preparng the mxture composton. Several methods for expermental data measurement of VLE have been developed and modfed for dfferent systems. 3

33 Hala et al. (1967), classfed several avalable VLE methods nto the followng categores: 1. Dynamc methods 2. Statc methods 3. Dstllaton methods 4. Flow methods 5. Dew and Bubble Pont methods A skeletal revew of these methods wll be made n ths chapter wth the man focus on the dynamc method for low pressure VLE, n partcular the recrculatng stlls. Raal & Mühlbauer, (1998), classfed stlls accordng to the phase crculaton through the equlbrum chamber. In other words, contnual crculaton s generally known as the dynamc method or flow method, otherwse t s a statc method. A systematc breakdown of some methods s shown n Fgure 2-1 below. VLE methods Dynamc Statc Sngle vapour pass Non-analytcal Sngle vapour & lqud pass Analytcal Fgure 2-1: Schematc descrpton of some VLE methods (Raal & Mühlbauer, 1994) 4

34 2.1.1 Statc Method The statc method can be subdvded nto statc analytcal method, n whch the compostons of both are sampled and analysed, and the statc synthetc method n whch samplng of the phases s not requred. In the statc synthetc method, the system pressure s the prncpal measurement. The statc-synthetc (non-analytc) method entals preparng a mxture of a partcular known concentraton, and allowng the equlbrum of phases to occur wthn a cell, usually at sothermal condtons. The exact lqud composton s calculated after makng allowances for vapour holdup (Raal and Ramjugernath, 2001). The vapour phase composton can then be calculated from P-x data. Calculaton of vapour phase composton from P-x data saves tme and effort and also elmnates the chances of thermodynamc consstency testng of the data. Snce only the measurement of the system pressure s requred n the statc synthetc or statc nonanalytcal method, the major dsadvantage of ths method s the problem of complete degassng of the system. The system has to be completely degassed whch s a tme consumng process and ts avodance leads to measurement of naccurate pressures. Fgure 2-2: The general prncples of a statc VLE equpment (Uus-kyyny, 2004) 5

35 2.1.2 Dew and Bubble Pont Method In ths method, the cell used s consdered to be of a varable volume placed n a constant temperature bath. The sample s placed n the cell and the volume of the cell s adjusted untl vaporzaton occurs. The pont and volume at whch vaporzaton starts to occur s found by observaton f the cell s of glass or by deducng t on the pressure volume plot. However snce the composton of the sample s predetermned, analyss of the phases s not requred. When a lqud mxture begns to bol, the composton of the vapour dffers from that of the lqud. The more volatle component wll preferentally bol off. Thus, as bolng contnues, there s a drop n the concentraton of the least volatle component. Consequently a rse n the bolng pont occurs. The temperatures over whch bolng occurs set the bubble and dew ponts of the mxture. Readers are referred to the work of Uus-Kyyny (2004) for more detals on the dew and bubble pont method. Fgure 2-3:The prncple of the dew and bubble pont method (Uus-kyyny, 2004) Dynamc Method VLE data measurement that employs crculaton of one or both vapour or lqud phase/s through the equlbrum chamber s known as the dynamc method or smply crculaton method (Hala et al., 1967). Developed by Carveth n 1899 (Carveth, 1899), the prncple of ts operaton nvolves dscharge of a lqud mxture nto a dstllng flask, boled to brng about separaton of the vapour phase. The vapour rses and condenses at the coolng arm of the stll nto a recever. The advantage of ths method s that t s flexble for both sothermal and sobarc operatons. 6