MEASUREMENT OF VISCOSITIES OF SATURATED METHANE-NONANE LIQUID MIXTURES AT ELEVATED PRESSURES WITH A CAPILLARY NI$CQ'v1ETER•·. By STUART EDWARD BENNETT Professional Degree Chemical and Petroleum Refining Engineering Colorado School of Mines Golden, Colorado 1966 Submitted to the faculty of the Graduate College of the Oklahoma State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August, 1969 OKI.AH OMA STATE UNIVERSITY LIBRARY NOV 5 1969 ~· ~,.,, .. , . .. , .,. '· ·---z·-.; ."'··, '".-;·.l,~~.... ... w,•• -,.;.•<;;t MEASUREMENT OF VISCOSITIES OF SATURATED METHANE-NONANE LIQUID MIXTURES AT ELEVATED PRESSURES WITH A CAPILLARY VISCOMETER Thesis Approved: hesis dviser ~t{tL Deana.a.~ of the Graduate College 729859 ii PREFACE The effect of viscosity on mass transfer rates in pro­ cesses such as absorption has been recognized by the hydro­ carbon processing industries. However, the behavior of viscosity under varying conditions of temperature, pressure, and composition is only partially understood. In particular, data and correlations are needed to more completely under­ stand the change in viscosity with composition for typical hydrocarbon absorption process components. This study presents an examination of the viscosity changes of liquid methane-nonane mixtures at pressures up to 1200 psia and . over a temperature r~nge o·f -30°F · to 78°F, The experimental apparatus built for the investigation used a Zeitfuchs style capillary viscometer installed in a pressure cell fitted with appropriate equipment to control operating conditions. I am indebted to Profi R. N. Maddox for the advice and assistance he has provided while serving as my research ad­ viser for this project. I would also like to thank Prof. J.B. West for his assistance while serving on my thesis review committee and for his cooperation during my transfer from the-University of Illinois. Also, my.research associ­ ate, James R.. Dearo, deserves special mention and thanks for invaluable assistance and patience during this investigation. iii The assistance of the OSU Research Apparatus Development Laboratory personnel during construction of the equipment is also recognized and appreciated. I thank the Natural Gas Processors Association for pro­ viding funds to finance the purchase and construction of the experimental apparatus required in the investigation. The financial assistance provided by the School of Chemical Engineering of Oklahoma State University in the form of a research assistantship and the fellowship provided by the National Collegiate Athletic Association were greatly appre­ ciated. I especially wish to thank my wife, Kathy, and my parents, Mr. and Mrs. Edward E. Bennett, for their encour­ agement, confidence, and advice.during my period of graduate study. 'TABLB OF· CONl'iNTS · Chapter . ·. Page l NTROOUCTIQN. • • • • • • • • • • • • • • • • . ... l I.I. .LITERATURE SURVEY • • . .. .. .. • • • • . ..... ... 3 HistoricalDevelopt11ent ••••••••••••••. • · 3 Previous Experimental .Investigations • • • • • • . • • 7 Viscosity Correlations, •••••••.••••••• · 9 EXPERIMENTAL APPARATUS. .. • • III. ,• .• . ... Materi*ls Tested •••••••••••••••• , , 18 Pressure Distribution System • ·• • . • • • • • • • • • 18 Pressure Cell. ~ •••• · • ·••• • • • • • • • • • • 19 · Liquid Injection System ••.•.. • • • • • • • • • • • 24 ·viscometer.•. , • • ;. • • .• • • • • • • • • • • ,., • • . 24· · ·. Temperature Controls . ~ . • . • • • · • • • . • • • • • • • • 28 Lighti~ • • • • . • .•. , , .·• • • • • • • • • • .• • • . • 30 EXPERIMENTAL PRO:SDURE •• IV. .. • • . ' ~ .•. .. .. • • • 31. System Preparation , . • . • • • • • • : • • .. • • ,. • • • • . 31 Measurement.. • • ~ ·• · • • • • • , • • • • • • • • ., ·• 33 DhmantU~ arid Cle•ning • • ·• • .,. • • • • . • • • • • .''·34 •' . v. RESULTS. AND DISCUSSION: OP RESULTS •• • • •.............. 3~ Construction of Equipment. · • .• • • • • • • • • " • , 35 Collectio,n of Viscqs1ty Data • , • • • , • • • •. • • .37 Absolute Viscosity a,havior. , • • , • • • • • .., • • 39 Surfa~e .. Teneion Viscosity Cor:rela'!:lon.~ , •••••• · 48 .•. •· ... •·. 52 • ... ... • • .. ~TURe. ·:.·. -~·-. ~ .... ,: ·• ·• •• .- ~_. • ·• ·•· -• ......... .-· ••••.• !$7· . •· ..... .. .. • • . .. .. .. .. ..... ' . • . • r .59 •..j .• •.•. · .• . • ti 42 -~ ' ,. 64 APPENDxx·,. ·""'. MEASUREMENT'REPROOUCIBILitv.. .·· ... ·.: ....... : . .. .. .. .. .. ··~ .. ~- . ~ ..... ~ ....... 49 Af'Pllf)IX D ··l!XPSRIMENTAL AND·CALCULATEO DATA oi • :• ·72. •. ' : . •·• ', .·. ..... , . ·. ... .· ' .111 . '. :~PI-U .. & •• ANALYSl,S .OP .oas. ·~• , ~ ..; ,: .~ .. ~ .·... ·. .. .. •·. .· 80 LIST OF TABLES . Table Page L Tabulated Viscosity Measurements q 41 II. Least Squares Analysis for Surface Tension - Viscosity Correlation .. ,, o • • • • • 49 I I I. Heise Gauge Calibration, , o 63 IVo Study of Reproducibility of Viscometer Measurements . o •••••••• o ••• 66 V. Viscometer Calibration. 70 VL Calculated Viscometer Constants .. I]) Q " 0 71 VII, Experimental Flow Times" .... " 73 vi LIST OF FIGURES Figure Page 1. Schematic Diagram of Experimental Apparatus~ .. 20 2. Detail of Pressure Cell .. 21 Detail of Observation Port Assembly .. 22 4. Schematic Drawing of Liquid Injection System 25 5. Zeitfuchs Style Viscotneter ........ 27 6. Kinematic Viscosity of Metha'ne-Nonane Bubble Po .int ti 9 O III O e 9 .. fi1 O ' GI • 'el 1!1 fl e C II GI «I 38 7' ·Absolute Viscosity of.Methane-Nonane Bubble Point Mixtures as a Function of Pressure .•. 43 Absolute Viscosity of Methane~Nonane Bubble Point Mixtures as a Function of Temperature. 44 9. Absolute Viscosity of Methane-Nonane Bubble Point Mixtures as a Function of Composition .. 45 10. Absolute Viscosity of Methane-Nonane Bubble. Poin.t Mixtures as a Function of Density ..•. 46 lL Absolute Viscosity of Methane-Nonane Bubble Point Mixtures as a Function of Composition and Pressure . · . ·. • . 47 '.t.2 ~ Logarithmof Surface Tension as a Function of Reciprocal Viscosity for Methane-Nonane Mixtures Q 111 0 tl 9 . 0 0 ~ II O ID C Q ti O e II . Q e so 13. Logarithm of Surface Tension as a Function of Reciprocal Viscosity for Methane~Butane MiX.ture-s ID a_ e GI C «i O e II II O e O Ii o • 0 0 11 51 vii CHAPTER I INTRODUCTION In September of 1964, Dr. James H~ Weber of the Univer­ sity of Nebraska prepared a literature survey for the Natural Gas Processors Association (NGPA) which was entitled Factors Affecting Absorber Performance (34.) .. On.pq.,ge]7. of the survey, Dr. Weber'referred to the importance of viscosity in determining mass transfer rates which in turn affect tray efficiencies in absorbers. In order to understand the effect of viscosity more completely, the Absorption Committee of NGPA desired vis­ cosity data for typical absorption oil components. The particular information.required by the NGPA was a determina­ tion of the.change in.vi~cosity of absorption oil-components as.the concentration of lighter hydrocarbons in the oil varied •. Primary emphasis was to .be placed on the study of binary liquid systems at equilibrium conditions. Measure­ ments were to be conducted in a hydrocarbon gas atmosphere (methane) at pressures up to 1500 psia and over a temperature range of -so0 p· to 1so°F. In this study the following procedure was followed. to obtain the required information. 1 2 1. An apparatus was built which used a capillary viscometer for obtaining viscosity data for the. liquid phase of a binary hydrocarbon system (n-methane and n-nonane) at the required temp- erature and pressure conditions. 2, Experimental values of kinematic viscosity for the methane-n-nonarie system over the required ranges of temperature and pressure were obtained with the apparatus .. 3, The absolute viscosity was calculated from kine­ matic viscosity and its variations with temperature, pressu_re, and compositions were studied. ';: 4. Absolute viscosity and surface tension were correlated . • ·1:·. CHAPTER II LITERATURE SURVEY Literature concerning this study of viscosity can be divided into three categories. One category encompasses the historical deveiopment of-viscometry in general and the capillary viscometer in particular. The second category in~ eludes the experimental work that has been conducted either under high pressures or with hydrocarbon mixtures; The third category includes past attempts to correlate viscosity data. A discussion of the literature in_all three categor- ies is presented in this chapter. Historical Development The foundations of viscometry were est~blished by Newton in the 1700's when he postulated his hypothesis of viscosity (21.} .•- _Barr (1) pres~nts the British ··Standards Institution .:frite'fpretai:16:n of· 'Newton's def:i.nition' cif the co~ . - efficient of ~isc6sity.~ ~ "The coefficient of viscosity is the numerical value of the tangential force on a unit-area of-­ two parallel planes at a unit distance apart · when the space bet~een these planes is filled with the liquid in question and one .of them moves with unit velocity in its own plane relatively to .the other." · The mathematical expression of Newton's hypothesis as re- 3 4 ported by Barr is (1) F = Force required v = Velocity of the plane X -- distance between.planes ~=dynamic or absolute viscosity A quantity which also appears· in.the present viscosity study is the "kinematic viscosity,'')), equal to the dynamic vis­ cosity divided by the density,p, ·of the_fluid. The common tlnit of dynamic viscosityJ)A, is called a poise in the cgs system (gm cm-l sec- 1). The corresponding unit of kinematic iiscosity