Liquid-Vapor Equilibrium Relations in the System Carbon-Dioxide - Hydrogen-Sulfide

90 Pages·02.626 MB·English

by  Bierlein, James Allison

LiquiD-vim jqpuisDxw ulatxors m m i m x
oanov dioxm - w tm am * u in n
ttm r to U o a
Prttmtad la Martial Yalflllaoat of tho laqulm iati
for tto Doicroo Doctor of Mlooophgr la tho
Graduate Sohool of tho Ohio ttato
ttolYorolty
Jmm Alllooa Slorlola, I.S ., M»to»
Tho Ohio ttato ttairorolty
1951
AArioor
%
TABLE OOHTKTTTS
Adcnowledfloenta
L ilt of Tables m
List of Illu stratio n s iY
Introduction and Summary 1
Apparatus and Procedure 3
Srperlmental Data 23
Die cue si on of B siults ^.7
Bibliography 55
Appendices
A. Calibration of Bxperlnental -Tube ?1
B. Calibration of Thermocouple 77
C. Calibration of Prassure Oauce 80
3>. tubs Loading Calculations 82
Autobiographical Bote 85
-1-
892479
ACPTOWIlDaHgHTS
I wish to exoress ny gratitude to By advissr, Profenr.or
Webeter B. Hay. Hi a patient guidance and a.,t«l stance, sometime*
rendered at considerable inconvenience to himself, facilitated
the work immerieureably.
Thanks are due to the U. 8. Air Force for perm itting the
after-ho'irs uee of laboratory fa c ilitie s and for general
adm inistrative cooperation in making it possible to carry out
the research.
Finally. X want to acknowledge the contributions of my
wife Bonnie. A laboratory widow for more than a year, she
accepted this unenviable status with rare understanding and
£;ood humor, and supplied aid and encouragement when they were
badly needed.
i d s i s i m m
Proportion of M aterial! 13
Saarpie Data Shoot 16
Uni quo Stotoo of tho Syeten 25
Kaperlaental Doto z6
Properties of Saturated Stateei Argument in
Temperature 29
Proportion of Saturated Statens Argument in
Prooouro
3*
Liquid-Vapor equilibria Ul
▼an laar Conotanto in Low-Tonneraturo Region *>5
Toot of van Lear Squatlon at Icepolnt U6
Tube Calibration Data 72
Tube Volume Ohart 75
Thermocouple Calibration 78
Calibration Chart for Thoraoeouplo 79
Oomprenolblllty Pactore 83
Topical Tube Loading Data
BU
- ill-
LIST ILLUSTRATIONS
£ T
Experimental Tub* 56
Compressor Block Assembly, Showing Tub* Seal
Arrangement 57
Schematic Diagram of Apparatus Assembled ’ for Ua* 5B
Buret for Me*aurine *nd DellTaring tea 59
Loading of Bxperimental Tube 60
Pressures of Saturated Statea 61
Holal Volumes of Saturated Statea 62
C ritical Statea of the Syatea 63
Saturated Molal Volume as a function of Composition 65
Saturation Preseure aa a function of Oomooeltlon 66
Saturation Tearoerature aa a function of Ooaiposltlon 67
Iaoaetrlc Bepreaentatlon of the Saturation Surfaces
of the fljystem 68
Compositions of fhaaes In equilibrium 69
Xoulllbrlua Batios for Phases in loulllbrlum 70
- I t-
XiqUID-TAPOH R^UI LIBRIUM RCIATI0H3 IK THE SYSTflM
CARBON DIOXIDE - HTBSOORV SULFIDE
INTRODUCTION AND SUMMARY
The Q uantitative study of vaoor-llouid equilibria and of
the phenomena In the c ritic a l region of fluids has played a
prominent role In the development of physical science. The
t
pioneer experimentation in th is field , begun about the middle
♦
of the nineteenth century, opened the way for the scien tific
analysle of the age-old a rt of d istilla tio n and stimulated the
development of the thermodynamics of solutions ae exemplified
by the classic contributions of Olbbs and van der tteals. Over
the years, theory and experiment have led to the genera11 ration
of much knowledge, from which pure science and the engineering
a rts have mutually benefitted. Yet much remains to be done in
the way of accumulating additional data and placing present
theory and technolo*y on a sounder basis.
The present trend toward the us#.of-higher pressures and
temperatures in the process industries, dictated mostly by
economic considerations of realizing b etter yields or using
more abundant raw m aterials, has emohaslzed the need for more
extensive inform ation on the eouillbrium properties of thermo­
dynamic systems under conditions aporoachlng the c ritic a l.
It is In this regime that available generallrations are least
reliab le, oad good experiment*! data are needed both as a
-1 -
nrectieal operating expedient and as g rist for the evolution
a^re satisfactory theoretical guidelines.
■if
hydrogen sulfide and carbon dioxide are present In many
natural petroleum reservoirs, and they tend to concentrate with
the light hydrocarbon fractions during the refining of the crudes.
The recovery of the hydrogen sulfide is becoming a n a tter of
increasing commercial importance because traditio nal sources of
sulfur are no longer adequate to meet the expanding demands for
th is element. Tor th is reason, it Is desirable to make avalloble
phase and equilibrium data for mixtures of hydrogen sulfide with
the various v o latile components froa which It is to be separated.
A number of recent ln v e stl^ tlo n s (1,2,3) have been devoted to
the determination of the behavior of binary systems of hydrogen
sulfide with the lower paraffin hydrocarbons under high pressure.
These researches comprise advances toward the accumulation of a
reliable fund of data for the processing of multicomponent systems
containing th is compound. The present investigation on the
hydrogen sulfide-carbon dioxide system is Intended to contribute
further to the attainm ent of th is goal. The only Information
heretofore available on the system in question wae the fragmentary
data of Steckel (h), who determined the Isothermal dew- and bubble-
point curves at sero degrees C and two lower temperatures; these
temperatures are below the range which Is ordinarily of oractlcal
interest to the industry.
In the present investigation, the pressure-volume-temperature
-2-
'behavior m i determined for the saturated states of eight mixtures
of hydrogen sulfide and carbon dioxide at temoeratures between the
Ice point and the crlcondentherm, ftiese data suffice to define
the equilibrium and volumetric relations of the system to a high
degree of precision, suitable for further ecien tlfic analysis
as well as for engineering purposes. It was found that the aysten
exhibits no azeotroplen. lfce rectificatio n of mixture* high In
hydrogen sulfide content should be relativ ely simple, as carbon
dioxide Is squeezed out strongly; mixtures containing over 0.8
mol fraction of carbon dioxide become increasingly d iffic u lt to
separate. The c ritic a l pressures and temoeratures of the mixtures
are Interm ediate between those of the pure components for every
composition, whereas the c ritic a l volume passes through a minimum.
The c ritic a l pressure curve Is of an unusual shape and has a point
of Inflection near the equlmolal composition.
APPARATUS AND PR0CIDUR1
Jcneral
The equipment and procedure used In th is Investigation
were essentially those developed by b y (5) and his students.
A very exhaustive description of the experimental techniques,
Including the manipulation of liquid samples, has been given by
H ill (6).
In principle, the method consists of confining a known mass
- 3-
of sample, of definite composition, over mercury In a caolllary
tub*. The sample la thermostated, and a known pressure la appllad.
After equilibrium la attalnad the volume la determined by maaaurln.fr
the length occupied by tha column of aanple; thla length la related
to tha volume by a prior calibration of tha tuba. Dev- and hubblap­
point phenomena can be d irectly observed through tha tube valla aa
the preeaure la changed, and It la possible to bracket the p-v-T
raluea for tha oaturated atataa of tha fluid an exactly aa tha
obeerrer desires, up to the lim its of accuracy with which the
aeparate variables can be meeaured.
Expertaestal Tube and Compressor Block
Tha core of tha apparatus la tha arparlmantal tube, which
serves an a container for the eaatple. Tha tube uaad In thla
Investigation wee conetructed from glass and hae tha
P yrm x
approximate dimensions ahovn In Figure 1. Tha cloaed and vaa
conetructed of special unlf orm-bore tubing and wea crlibrated
so that tha volume was known as a function of distance from tha
tip. D etails of tha calibration are given In Appendix A.
Tha calibrated portion of tha tube was aealed to an open
lower eeetlon consisting of a thickened co llar, a large gas
reservoir, and a male taner Joint.
The experimental tuba, when In use, was mounted In a
Compressor block, which served to hold I t firmly In an arrangement
of e la stic seals so that oreaaure could be applied to the sample.
The compressor Mock o orisl ste-* of two thl ck-walj ed steel cylinder*
(a ) and (B) join*"* by n check valve (r) to form « steel U-tuhe
r.ft eeen In Figure 2. The e.v-,f rl t rrte 1 tube la shown In place In
the left-hand cylinder. The Trlr/iry cclnt of suspension w a
around the thickened collar (I) of the tube. The large bulb at
the lower end m i conroletely surrounded and filled with mercury,
no there were no pressure differential* across It. The large
rubber stopoer (L) constituted the primarv pressure seal; i t
>ila;i gave la te ra l, hut not v ertical, puoport to the tube.
The assembly la h*led (G) supMled the main mechanical suooort.
It i*. shown resting on the shoulder of the left leg of the comoressor
Mock and is elso shewn in o artlal detail in the Insert of Figure 2,
In order to place the bottom of the euoport assembly between the
co llar (I) and the bulb of the experimental tube, the cun assembly
(Q) was constructed of a tvo-oiece sleeve, (?) and (R), sunoorting
the sp llt-rln g (H) and the rubber washer (H). The hole through
the sp lit-rin g (^) was made smeller in diameter than the ro ller
(I) of the experimental tube In order to prevent the tube from
sli oping through.
The rubber washers (H) *>nd (J) Isolated the experimental
tube from any direct contact vith .netal. The uoper washer (J)
and the steel ring (K) formed the uoper Bupoort which restrained
the tube from moving upward when nreeeurn was aoolled to the
sample. The indented center portion of the ateel ring (K) also
lim ited lot ere 1 movement. Thus, the experimental tube wae
5
-