THE CORRELATION OF TRUE BOILING POINT AND
EQUILIBRIUM FLASH VAPORIZATION CURVES
FOR SOME CANADIAN CRUDE OILS
by
WALTER HAYDUK
A THESIS SUBMITTED IN PARTIAL FULFILMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF APPLIED SCIENCE
i n t h e Department
of
Chemical E n g i n e e r i n g
We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o
the standard r e q u i r e d from candidates f o r
t h e degree o f MASTER OF APPLIED SCIENCE
Members o f t h e Department o f
Chemical E n g i n e e r i n g
THE UNIVERSITY OF BRITISH COLUMBIA
October,
1955.
ABSTRACT
An Ofchmer r e c i r c u l a t i n g s t i l l and a s t a n d a r d
packed column f r a c t i o n a t i n g u n i t were us«d i n d e t e r m i n i n g t h e e q u i l i b r i u m f l a s h v a p o r i z a t i o n and t r u e
b o i l i n g p o i n t c u r v e s r e s p e c t i v e l y , f o r e i g h t samples
o f crude o i l s from p r o d u c i n g o i l - f i e l d s i n A l b e r t a .
The EFV curves, a t 10 mm. a b s o l u t e p r e s s u r e were a l s o
o b t a i n e d f o r t h e s e samples.
Determinations a t atmospheric
p r e s s u r e were
used f o r m o d i f y i n g Okamoto and Van W i n k l e ' s
correl-
a t i o n , w h i c h a l l o w s t h e p r e d i c t i o n o f t h e EFV c u r v e s
f r o m t h e TBP c u r v e s , f o r a p p l i c a t i o n t o crude
oils.
The c o r r e l a t i o n r e l a t e s t h e 50 p e r c e n t p o i n t s and
the s l o p e s o f t h e two c u r v e s . I n s p i t e o f i t s s i m p l i c i t y , i t r e s u l t s i n p r e d i c t e d c u r v e s o f good a c c u r a c y .
I t i s b e l i e v e d t h a t t h i s method i s s u i t a b l e f o r a
l a r g e number o f crudes and can g i v e dependable phase
equilibrium data.
ACKNOWLEDGEMENTS
A p p r e c i a t i o n i s expressed f o r
t h e s u g g e s t i o n s and guidance g i v e n by
Dr. L. W. S h e r a i l t under whose s u p e r v i s i o n t h i s r e s e a r c h was p e r f o r m e d .
Acknowledgement i s a l s o made t o t h e
I m p e r i a l O i l Company o f Canada and t h e
S t a n d a r d O i l Company o f Canada who
s u p p l i e d t h e samples.
TABLE OF CONTENTS
Page
I,
II.
III.
INTRODUCTION
1 #
PREVIOUS CORRELATIONS
3.
APPARATUS
5.
(a) TBP
Still
(b) EFV S t i l l
(c) Temperature Measurement
IV.
V.
SAMPLES AND MATERIALS
X
PROCEDURE
(a) TBP
6
#
20.
Still
(b) EFV S t i l l
(c) C a l i b r a t i o n o f TBP column
VI.
•VII.
VIII.
RESULTS
DISCUSSION OF RESULTS
BIBLIOGRAPHY
29.
5
6
#
6
1 #
TABLES
Page
T a b l e I N u m e r i c a l Data f o r TBP and EFT E x p e r i m e n t a l
Points
51
T a b l e I I N u m e r i c a l Data f o r TBP and EFV C o r r e l a t i o n s
55
ILLUSTRATIONS
1.
Diagram o f TBP S t i l l , F i g . 1.
6
2.
Diagram o f EFV S t i l l , F i g . 2.
10
3.
C a l i b r a t i o n c u r v e f o r thermometers, F i g . 3.
14
4.
Cox c h a r t , F i g . 4.
23
5.
McCabe-Thiele Method f o r TBP
column
E f f i c i e n c y , F i g . 5.
6.
28
C o r r e l a t i o n o f TBP and EFV 50 p e r c e n t points.,
Fig.
6.
30
7.
C o r r e l a t i o n o f TBP and EFV s l o p e s , F i g . 7.
31
8.
A t m o s p h e r i c and 10 mm.
32
9.
Phase Diagrams f o r crude o i l samples, F i g . 9.
41
10.
A t m o s p h e r i c TBP and EFV c u r v e s , F i g . l O a - l O h .
43
EFV c u r v e s , F i g . 8a-8h.
1.
I . INTRODUCTION
Such o p e r a t i o n s as t h e v a p o r i z a t i o n and c o n d e n s a t i o n
of hydrocarbon m i x t u r e s a r e b a s i c i n t h e p r o d u c t i o n and
r e f i n i n g of petroleum.
I t i s o f t e n necessary t o p r e d i c t vapor-
l i q u i d phase e q u i l i b r i u m c o n d i t i o n s i n p r o c e s s d e s i g n c a l c u t
l a t i o n s and i n a n a l y z i n g commercial o p e r a t i o n s . The a b i l i t y
t o p r e d i c t a c c u r a t e l y t h e p r o d u c t d i s t r i b u t i o n o f a new crude
mixture, or the operating conditions t o give desired y i e l d s
of
c e r t a i n f r a c t i o n s , i s o f prime economic i m p o r t a n c e .
For
t h e s o l u t i o n o f problems concerned w i t h t h e phase e q u i l i b r i a
of
complex h y d r o c a r b o n m i x t u r e s , e m p i r i c a l methods based on
t h e common l a b o r a t o r y , d i s t i l l a t i o n s , m u s t s t i l l be used.
Petroleum d i s t i l l a t i o n processes i m v a r i a b l y
the p r e h e a t i n g o f t h e s t o c k o r crude w i t h subsequent
i n t h e d i s t i l l a t i o n column.
entail
flashing
Calculations f o r the conditions
of t e m p e r a t u r e and p r e s s u r e r e q u i r e d t o g i v e a p a r t i c u l a r
residuum a r e s i m p l i f i e d by t h e use o f e q u i l i b r i u m flash£ v a p o r i z a t i o n (EFV) c u r v e s .
These c o n s i s t o f p l o t s showing
curves of percent v a p o r i z e d versus t h e v a p o r - l i q u i d
temperature.
isobaric
equilibrium
The s m a l l l a b o r a t o r y EFV s t i l l d e s i g n e d by
Othmer (15) has proven t o be s u c c e s s f u l f o r o b t a i n i n g EFV c u r v e s
at
subatmospheric p r e s s u r e s .
S i n c e subatmospheric p r e s s u r e s
r
are
g e n e r a l i n p e t r o l e u m r e f i n i n g , t h e EFV c u r v e s a r e w i d e l y
applicable.
Because t h e s e s t i l l s a r e n o t as yfct s t a n d a r d
l a b o r a t o r y equipment and because o f t h e e x p e r i e m e n t a l d i f f i c u l t i e s
i n v o l v e d , EFV curves a r e u s u a l l y p r e d i c t e d from t h e more
common t r u e b o i l i n g p o i n t
curves.
(TBP) and A.S.T.M. d i s t i l l a t i o n
C o r r e l a t i o n s f o r p r e d i c t i n g EFV c u r v e s which can be
a p p l i e d t o petroleum f r a c t i o n s are u n s a t i s f a c t o r y f o r crudes.
A s u i t a b l e c o r r e l a t i o n f o r crudes was t h e s u b j e c t o f t h i s
investigation.
reproducible
Because t h e A.S.T.M. d i s t i l l a t i o n i s n o t v e r y
and i s d i f f i c u l t t o complete f o r c r u d e s , t h e TBP
d i s t i l l a t i o n was chosen as b e i n g t h e more s u i t a b l e f o r
correlating
purposes.
3.
I I . PREVIOUS CORRELATIONS
Two t y p e s o f e m p i r i c a l c o r r e l a t i o n s a p p l y i n g g e n e r a l l y
t o petroleum f r a c t i o n s are a v a i l a b l e i n the l i t e r a t u r e f o r
p r e d i c t i n g t h e EFV curve a t a t m o s p h e r i c p r e s s u r e .
One t y p e
uses t h e i n t e r s e c t i o n p o i n t and t h e s l o p e s o f t h e f l a s h and
A.S.T.M. o r TBP c u r v e s , and t h e o t h e r uses t h e 50 p e r c e n t b o i l i n g
p o i n t s and s l o p e s .
Beiswenger
(17)
I n t h e method proposed by Piroomov and
t h e f l a s h c u r v e was assumed t o be a s t r a i g h t
l i n e and was l o c a t e d by e s t i m a t i n g t h e p o i n t o f i n t e r s e c t i o n and
i t s s l o p e from t h e smoothed A.S.T.M. o r TBP d i s t i l l a t i o n s .
t h e method proposed by N e l s o n and Souders (11)
In
and m o d i f i e d by
. K a t z and Brown (9) t h e EFV c u r v e was a l s o assumed t o be a
s t r a i g h t l i n e and was p r e d i c t e d by e s t i m a t i n g i t s 50 p e r c e n t
p o i n t and s l o p e from t h e 50 p e r c e n t p o i n t and 10-70 p e r c e n t
s l o p e o f t h e A.S.T.M. o r TBP d i s t i l l a t i o n s .
Experiment aLL
EFV d a t a i n d i c a t e t h a t t h e l i n e s a r e not a c t u a l l y
straight
a l t h o u g h t h e c u r v a t u r e f o r a l a r g e p o r t i o n o f t h e curve i s
s l i g h t (16).
I n t h e method p r e s e n t e d by P a c k i e (16) and r e v i s e d
by E d m i s t e r and P o l l o c k (4) t h i s d e p a r t u r e from a s t r a i g h t
line
was t a k e n i n t o c o n s i d e r a t i o n .
None o f t h e e x i s t i n g methods o f . c o r r e l a t i o n a r e
constructed t o apply s p e c i f i c a l l y f o r crudes.
The E d m i s t e r
and P o l l o c k c o r r e l a t i o n , f o r example, uses t h e TBP s l o p e s as
parameters
on a p l o t o f TBP 50 p e r c e n t v e r s u s t h e d i f f e r e n c e
i n TBP and EFV 50 p e r c e n t p o i n t s .
The s l o p e s , however, have
t o o s m a l l a range t o account f o r t h e s t e e p s l o p e s o f TBP c u r v e s
4.
f o r crudes.
As a r e s u l t a s i m p l i f i e d c o r r e l a t i o n by Okamoto
and Van W i n k l e
(14)^which shows g e n e r a l
relationships
between TBP and EFV c u r v e s , has been chosen as a b a s i s f o r
the present c o r r e l a t i o n .
I n t h i s c o r r e l a t i o n the' EFV 50 p e r c e n t
p o i n t i s determined from the TBP 50 p e r c e n t points, and t h e 10-70
p e r c e n t s l o p e i f r o m t h e TBP. 10-70 p e r c e n t s l o p e .
The v a l u e s
f o r t h e crude o i l s a r e compared d i r e c t l y w i t h t h e c o r r e l a t i o n
of Okamoto and Van W i n k l e .
5
III.
APPARATUS
(a) True B o i l i n g P o i n t S t i l l
The TBP
apparatus c o n s i s t s of an a l l - g l a s s
analytical
d i s t i l l a t i o n u n i t w i t h an e f f i c i e n t f r a c t i o n a t i n g column
s u i t a b l e f o r crude e v a l u a t i o n .
Accessories include a
l i q u i d - d i v i d i n g s t i l l - h e a d f o r convenient r e f l u x
control,
a vacuum u n i t w i t h a p r e s s u r e c o n t r o l l e r and d r y - i c e t r a p ,
a mercury manometer, and a m a n i f o l d p e r m i t t i n g s e p a r a t e
e v a c u a t i o n o f t h e d i s t i l l a t e r e c e i v e r d u r i n g vacuum
operation.
F i g u r e 1 shows the arrangement o f t h e
apparatus.
A g l a s - c o l h e a t e r p r o v i d e s t h e n e c e s s a r y heat i n p u t t o
t h e s t i l l - p o t ; f o r r e d u c i n g t h e l a r g e heat l o s s a t t h e
h i g h temperatures
used, a u x i l i a r y r i b b o n h e a t e r s
covered
w i t h i n s u l a t i o n e n c l o s e t h e column and s t i l l - h e a d .
u n i t i s compact and simple i n o p e r a t i o n , d e s i g n e d
The
to
o p e r a t e w i t h a minimum amount o f a t t e n t i o n .
The
column i s a s t a n d a r d type 1 - i n c h s i l v e r e d vacuum-
j a c k e t e d column packed t o h e i g h t o f 22 i n c h e s w i t h
inch glass helices.
1/8
Twelve e x p a n s i o n b e l l o w s a l o n g
the
outer j a c k e t permit the necessary expansion f o r the h i g h
temperatures
encountered
i n crude d i s t i l l a t i o n .
The
performance o f t h e column when c a l c u l a t e d by t h e McCabie
and T h i e l e method (10) u s i n g a benzene-carbon t e t r a c h l o r i d e
t e s t m i x t u r e , i s 11.4
theoretical plates.
corresponds t o o p e r a t i o n a t a t m o s p h e r i c
T h i s performance
pressure, at
t o t a l r e f l u x , and a d i s t i l l a t i o n r a t e o f about 1500
ml.
REFLUX TIMER
V"
s
POTENTIOMETER
7.
p e r hour, the r a t e n o r m a l l y used.
The
column i n c o n j u n c t i o n
w i t h the r e f l u x c o n t r o l s t i l l - h e a d has an a v a i l a b l e f e e d
c a p a c i t y c o n s i d e r a b l y h i g h e r than t h a t used i n t h e s e d e t e r m i n a t i o n s ; however, f o r convenience,
(2 l i t r e s ) were d i s t i l l e d .
r e l a t i v e l y s m a l l samples,
At 10 mm.
d i f f e r e n c e i n column o p e r a t i o n was
p r e s s u r e no
obsejrved.
significant
In a l l respects
t h e column o p e r a t e d s u c c e s s f u l l y .
An a u t o m a t i c
l i q u i d - d i v i d i n g s t i l l - h e a d (manu-
f a c t u r e d by t h e G l a s s E n g i n e e r i n g L a b o r a t o r i e s , San C a r l o s ,
C a l i f o r n i a ) (3) a c t i v a t e d by a s o l e n o i d , a l o n g w i t h a w a t e r c o o l e d condenser, p r o v i d e s any d e s i r e d r e f l u x r a t i o .
The
s t i l l - h e a d i s so c o n s t r u c t e d t h a t t h e vapor s t r e a m r i s i n g f r o m
the column f l o w s p a s t a g r o u n d - j o i n t p a r t i a l - i m m e r s i o n
thermometer, t h e n d i r e c t l y t o the condenser.
f l o w s down t h r o u g h
The
condensate
the s t i l l - h e a d by a d i f f e r e n t r o u t e ,
p a s s i n g t h r o u g h a s m a l l t i p p i n g f u n n e l which n o r m a l l y
directs
t h e l i q u i d stream t o the c e n t r e o f t h e column p a c k i n g .
Contained
i n t h e t i p p i n g f u n n e l i s a p i e c e of s o f t i r o n w h i c h
can be a t t r a c t e d by a s o l e n o i d o u t s i d e the s t i l l - h e a d .
When
so a t t r a c t e d the f u n n e l d i r e c t s the l i q u i d s t r e a m t h r o u g h
vapor t r a p t o the product r e c e i v e r .
The
a
solenoid i s activated
by an e l e c t r o n i c t i m e r w h i c h s u p p l i e s power f o r t h r e e seconds
at a time.
R e f l u x c o n t r o l i s e f f e c t e d by changing t h e
on-off
time r a t i o of the t i m e r and assuming t h a t t h i s corresponds
the l i q u i d r e f l u x r a t i o o b t a i n e d .
to
T e s t s have i n d i c a t e d t h a t
the r e f l u x r a t i o - c o n t r o l l e r g i v e s a somewhat h i g h e r r e f l u x
8.
r a t i o t h a n i n d i c a t e d by t h e t i m e r ( 3 ) ; however, t h i s does
n o t s i g n i f i c a n t l y e f f e c t t h e o p e r a t i o n o f t h e column.
The vacuum u n i t i n c l u d e d an o i l - f i l l e d
fore-pump-
t y p e , vacuum pump, a surge t a n k , a C a r t e s i a n - t y p e manostat,
and a d r y - i c e t r a p connected i n s e r i e s .
equipped
The surge t a n k was
w i t h a needle v a l v e t o a l l o w an approximate
p r e s s u r e adjustment t o a v a l u e somewhat l o w e r t h a n r e q u i r e d
i n t h e u n i t ; t h e p r e s s u r e was m a i n t a i n e d p r e c i s e l y by t h e
manostat.
The d r y - i c e t r a p was used i n t h e main e v a c u a t i n g
l i n e t o p r e v e n t t h e escape o f l i g h t f r a c t i o n s .
The p r e s s u r e
i n t h e u n i t was measured by a mercury manometer c o n n e c t e d
t o t h e vacuum l i n e from t h e condenser.
9.
(b)Equltibrium Flash:Vaporization
Still
The most s u c c e s s f u l l a b o r a t o r y v a p o r - l i q u i d
e q u i l i b r i u m s t i l l s almost i n v a r i a b l y employ condensate r e circulation.
is
The vapor i n e q u i l i b r i u m w i t h t h e b o i l i n g
liquid
passed i n t o a condenser, and t h e condensate i s c o l l e c t e d i n
a r e s e r v o i r from which i t i s r e c i r c u l a t e d back i n t o t h e b o i l i n g
liquid.
the
When t h e e n t i r e s t i l l has r e a c h e d a s t e a d y s t a t e ,
s a t u r a t e d v a p o r r i s i n g from t h e b o i l i n g l i q u i d i s o f t h e
same c o m p o s i t i o n as t h e r e c i r c u l a t i n g condensate, and i s a t
the
same t e m p e r a t u r e as t h e b o i l i n g l i q u i d .
The v a p o r - l i q u i d
still
d e s i g n e d by Othmer.^(l$)) f o r t h e d e t e r m i n a t i o n o f EFV c u r v e s o f
crudes and p e t r o l e u m f r a c t i o n s e n t a i l s two b a s i c m o d i f i c a t i o n s :
a method o f v a r y i n g t h e volume o f condensate h e l d up i n t h e
r e s e r v o i r , and o f a c c u r a t e l y d e t e r m i n i n g t h i s volume w i t h o u t
interrupting the operation of the s t i l l .
A graduated r e s e r v o i r
w i t h a c a p i l l a r y stopcock i n the r e c y c l e l i n e e f f e c t i v e l y
these problems.
solve
The Othmer s t i l l a l o n g w i t h a u x i l i a r y e q u i p -
ment i n c l u d i n g a vacuum pump, surge t a n k , d r y - i c e t r a p and
manometer, i s shown i n F i g u r e 2.
The s t i l l
;
c o n s i s t s of a complete.pyrex g l a s s u n i t :
a 500 m l . s t i l l - p o t , vapor-arm, p r i m a r y condenser, g r a d u a t e d
r e c e i v e r , and r e f l u x l i n e .
Nichrome r e s i s t a n c e h e a t e r s p r o v i d e
e x t e r n a l h e a t i n g t o t h e s t i l l - p o t , vapor-arm, and r e f l u x
line;
these s e c t i o n s are a l s o i n s u l a t e d w i t h asbestos l a g g i n g coated
w i t h aluminum p a i n t t o p r e v e n t e x c e s s heat l o s s by r a d i a t i o n .
4
11.
An i n t e r n a l nichrome r e s i s t a n c e h e a t e r e f f e c t s smooth b o i l i n g ,
w i t h o u t bumping o f o r s u p e r h e a t i n g o f even s m a l l
liquid
volumes.
The bottom s e c t i o n of the s t i l l - p o t i s f a b r i c a t e d
w i t h a s m a l l e r bubble so that the d e p t h of l i q u i d
i s sufficient
f o r h e a t i n g and a c c u r a t e l y measuring t h e t e m p e r a t u r e when
most of t h e change i s i n the condensate r e s e r v o i r .
The
vapor-
arm i s o f a s i z e determined by two r e q u i r e m e n t s : t h a t t h e
p r e s s u r e drop o f t h e vapor p a s s i n g t o t h e r e s e r v o i r s h o u l d be
n e g l i g i b l e , and t h a t t h e t o t a l volume o f t h e v a p o r i n t h e
f r e e space o f t h e s t i l l - p o t and vapor-arm
s h o u l d be s m a l l enough
t o i n t r o d u c e n e g l i g i b l e e r r o r i n t h e l i q u i d volume measurement.
The p r e s s u r e drop a c r o s s the vapor-arm depends on t h e v a p o r i z a t i o n r a t e w h i c h , a t low p r e s s u r e s (10 mm),
can be c o n s i d e r a b l e ;
f o r t h i s reason a uniform slow d i s t i l l a t i o n r a t e i s i m p e r a t i v e .
The e r r o r i n t r o d u c e d by n e g l e c t i n g t h e amount of vapor i n t h e
s t i l l i n measuring t h e condensate volume c o r r e s p o n d s t o l e s s
t h a n 5 n i l . o f condensate d u r i n g adverse c o n d i t i o n s ( 1 5 ) .
A
c o r r e c t i o n can be a p p l i e d i n v e r y p r e c i s e work; however, t h i s
i s u s u a l l y not n e c e s s a r y s i n c e i t i s d t h e o r d e r o f a c c u r a c y
for
r e a d i n g the volume i n t h e r e s e r v o i r .
A t reduced p r e s s u r e s ,
t h i s e r r o r g r e a t l y d e c r e a s e s i n magnitude.
The condenser i s c o n s t r u c t e d i n two p a r t s f o r h a n d l i n g
crudes o r heavy f r a c t i o n s .
The p r i m a r y condenser can be
o p e r a t e d a t a temperature j u s t s u f f i c i e n t t o condense t h e h i g h e r
b o i l i n g p o r t i o n o f the vapors and s t i l l a l l o w t h e
condensate
t o f l o w f r e e l y down the w a l l s w i t h o u t f r e e z i n g out t h e waxy
.material.
The more v o l a t i l e p o r t i o n i s condensed i n the
secondary condenser c o o l e d t o a l o w e r t e m p e r a t u r e .
Since a
'small p o r t i o n o f t h e crude o i l s c o n s i s t s o f a h i g h l y v o l a t i l e
f r a c t i o n , t h e d r y - i c e t r a p s e r v e s as an a u x i l i a r y condenser;
d u r i n g 10 mm.
p r e s s u r e o p e r a t i o n w i t h l i g h t crudes as much
as 25 m l . o f condensate was c o n s i s t e n t l y c o l l e c t e d i n t h e t r a p .
The volume was c a r e f u l l y measured
and added t o t h a t i n t h e
r e s e r v o i r ; i t was i m p r a c t i c a l t o attempt t o keep t h i s
volatile
f r a c t i o n i n the r e s e r v o i r because i t b o i l e d a t t h e r e s e r v o i r
temperature.
The p r e s s u r e i n t h e u n i t was measured by an a b s o l u t e
manometer and m a i n t a i n e d at a c o n s t a n t v a l u e by a C a r t e s i a n t y p e manostat.
(c)
Temperature Measurement
Three d e v i c e s a r e commonly used f o r measuring
t e m p e r a t u r e s , t h e mercury thermometer, t h e r m o c o u p l e , and
r e s i s t a n c e thermometer.
The mercury thermometer i s a v a i l a b l e
f o r use e i t h e r as a t o t a l - i m m e r s i o n o r a p a r t i a l - i m m e r s i o n
thermometer.
I n b o t h cases s i m i l a r problems a r e p r e s e n t e d i f
v e r y p r e c i s e t e m p e r a t u r e measurement of t h e v a p o r phase i n a
vapor-liquid equilibrium determination i s required.
It is
d i f f i c u l t t o construct a s t i l l - h e a d or s t i l l - p o t that allows
adequate c i r c u l a t i o n of t h e vapor o r l i q u i d around t h e s e c t i o n
o f the thermometer s p e c i f i e d f o r immersion.
The
partial-
immersion thermometer u s u a l l y c r e a t e s a vapor p o c k e t where
13.
i t e n t e r s t h e s t i l l - h e a d ; t h e emergent stem i s a l s o exposed
to v a r i a b l e temperatures.
These problems l i m i t t h e use o f
mercury thermometers i n v e r y p r e c i s e work.
B o t h t h e thermocouple and r e s i s t a n c e thermometer
can
g i v e n h i g h l y a c c u r a t e t e m p e r a t u r e measurements.
the
r e s i s t a n c e thermometer o f f e r s t h e g r e a t e s t a c c u r a c y a s
w e l l as maximum r e l i a b i l i t y
Although
and r e p r o d u c i b i l i t y , t h e t h e r m o c o u p l e
i s o f more g e n e r a l use because i t i s l e s s b u l k y , has l i t t l e
temperature l a g ,
and r e q u i r e s t h e use o f o n l y a p o t e n t i o m e t e r .
The r e s i s t a n c e thermometer i s e s p e c i a l l y s u i t a b l e f o r c a l i b r a t i n g
purposes.
I n b o t h t h e TBP and EFV d e t e r m i n a t i o n s p a r t i a l immersion thermometers were used t o measure t h e v a p o r - l i q u i d
e q u i l i b r i u m temperatures.
The a c c u r a c y d e s i r e d , * 1.0°F, i n
s p i t e o f t h e i n h e r e n t p o s s i b l e e r r o r , was r e a d i l y o b t a i n e d as shown
when t h e s e thermometers were c a l i b r a t e d a g a i n s t t h e N a t i o n a l
Bureau o f S t a n d a r d s No. 169314; r e s i s t a n c e thermometer.
c a l i b r a t i o n c u r v e s appear i n F i g u r e 3.
The
The thermometers were
used i n p r e f e r e n c e t o t h e r m o c o u p l e s because t h e o r i g i n a l
d e s i g n s o f both u n i t s i n c l u d e d g r o u n d - j o i n t p a r t i a l - i m m e r s i o n
thermometers.
These were c o n v e n i e n t - because o f ease i n
r e a d i n g t h r o u g h o u t t h e whole range o f t e m p e r a t u r e s e n c o u n t e r e d .
I n t h e EFV a p p a r a t u s a s p e c i a l advantage o f t h e u s e
of
a p a r t i a l - i m m e r s i o n thermometer was t h a t t h e l i q u i d temper-
ature i n the s t i l l
c o u l d be watched and checked r e a d i l y w h i l e
a d j u s t m e n t s were made t o t h e h e a t e r s .
Other temperatures
c o u l d be measured by t h e r m o c o u p l e s l o c a t e d a t v a r i o u s p o i n t s
CALIBRATION
OF
THERMOMETERS
15.
o f t h e s t i l l - p o t , vapor-arm and r e c y c l e l i n e a t t h e g l a s s insulation interface.
By means o f a m u l t i p l e - s w i t c h and Leeds
and N o r t h r u p t y p e K p o t e n t i o m e t e r , t h e t e m p e r a t u r e a t any
p o i n t r e q u i r e d c o u l d be o b t a i n e d .
An a u x i l i a r y
thermometer
was p l a c e d i n t h e vapor-arm thermometer w e l l by w h i c h a check
on t h e e x t e n t o f s u p e r h e a t i n g c o u l d be made.
The TBP u n i t r e q u i r e d a p a r t i a l - i m m e r s i o n
thermometer
s p e c i f i e d t o f i t the s t i l l - h e a d ; the s t i l l - h e a d i s designed
t o reduce t h e thermometer
The thermometer
e r r o r due t o poor v a p o r c i r c u l a t i o n .
i s centred i n t h e vapor-stream a l l o w i n g a
maximum amount o f c o n t a c t .
Another thermometer
was used t o
g i v e an approximate i n d i c a t i o n o f t h e t e m p e r a t u r e o f t h e
ribbon heater surrounding the s t i l l - h e a d .
The crude charge
t e m p e r a t u r e was measured by means o f an i r o n - c o n s t a n t a n
thermo-
couple and p o t e n t i o m e t e r . T h i s thermocouple was used o n l y as
an approximate check f o r k e e p i n g t h e charge temperature below
650°F and, t h e r e f o r e , was n o t c a l i b r a t e d .
16.
IV.
SAMPLES AND MATERIALS
(a)
Crude O i l Samples
E i g h t samples o f A l b e r t a crude o i l were
analyzed.
Assurance was g i v e n t h a t t h e samples
were drawn t o g i v e r e p r e s e n t a t i v e composite
of t h e o i l - f i e l d o r p i p e l i n e .
samples
Storage i n a c o o l
place avoided excessive vapor l o s s .
m a t i o n about t h e samples i s l i s t e d
Relevant i n f o r
below:
API G r a v i t y
1. Pembina crude - r e p r e s e n t a t i v e
sample
from Pembina P i p e l i n e s t r e a m d e l i v e r e d i n 10 g a l l o n drum August
16, 1955, by I m p e r i a l O i l Company
38.0
Limited.
2. W i z a r d Lake crude - r e p r e s e n t a t i v e
sample
from b a t t e r y r e c e i v i n g crude from
s e v e r a l producing w e l l s i n the Wizard
Lake f i e l d d e l i v e r e d i n 10 g a l l o n
drum August 16, 1955, by I m p e r i a l
O i l Company L i m i t e d .
37.5
3. Leduc-Woodbend crude - r e p r e s e n t a t i v e
sample from I m p e r i a l P i p e L i n e
Leduc
g a t h e r i n g system d e l i v e r e d i n 10 g a l l o n
drum August 16, 1955,
Company L i m i t e d .
by I m p e r i a l O i l
40.1
API G r a v i t y
4. Texaco P i p e l i n e crude - r e p r e s e n t a t i v e
sample o f crude m i x t u r e from Texaco
P i p e L i n e b a t t e r y as R e c e i v e d t h r o u g h
Trans-Mountain P i p e L i n e , d e l i v e r e d
i n 5 g a l l o n can J u l y , 1955, by S t a n d a r d
O i l Company L i m i t e d .
40.6
5. Redwater crude - r e p r e s e n t a t i v e sample o f
crude from I m p e r i a l P i p e L i n e
Redwater
system as r e c e i v e d t h r o u g h Trans M o u n t a i n
P i p e l i n e , d e l i v e r e d i n 5 g a l l o n can J u l y ,
1955,
hy S t a n d a r d O i l Company L i m i t e d .
35»5
6« S t e t t l e r crude - r e p r e s e n t a t i v e sample o f crude
from S t e t t l e r f i e l d d e l i v e r e d i n 5 g a l l o n
can i n 1952, by I m p e r i a l O i l Company
Limited.
7. Joseph Lake crude
28.8
- r e p r e s e n t a t i v e sample o f
crude from Joseph Lake f i e l d d e l i v e r e d
i n 5 g a l l o n c a n i n 1952 by I m p e r i a l O i l
Company L i m i t e d .
8. Golden S p i k e crude
- representative
of crude from Golden S p i k e f i e l d
37*3
sample
delivered
i n 5 g a l l o n can i n 1952 by I m p e r i a l O i l
Company L i m i t e d .
38.9
S i n c e b o t h t h e TBP and EFV curves were t o be d e t e r m i n e d
on a volume p e r c e n t b a s i s , a c c u r a t e measurement o f t h e
volume o f crude charge t o t h e s t i l l s was r e q u i r e d .
The
18.
charge p o r t i o n s t o t h e TBP
s t i l l s were 2000 m l .
and EFV
and
500 m l . , r e s p e c t i v e l y . S i n c e the samples were a t an approximate t e m p e r a t u r e of 60°F and not v e r y v i s c o u s , t h e y were
poured d i r e c t l y i n t o a g r a d u a t e d c y l i n d e r o f a p p r o p r i a t e
s i z e t o a l e v e l somewhat h i g h e r t h a n the volume t o
delivered.
When the g r a d u a t e was
emptied and o i l a l l o w e d
t o d r a i n t o t h e bott©m'f the r e m a i n i n g volume c o u l d
estimated.
be
be
By p r a c t i c e t h e volume of charge r e q u i r e d c o u l d
be r e a d i l y o b t a i n e d by t h i s method.
(b) Benzene and Carbon T e t r a c h l o r i d e
'A. t e s t m i x t u r e
was
of benzene-carbon t e t r a c h l o r i d e
used t o determine t h e e f f i c i e n c y o f the TBP
column.
P u r i f i c a t i o n was
distillation
required to obtain a r e f r a c t i v e
i n d e x f o r the benzene w h i c h compared f a v o u r a b l y w i t h p u b l i s h e d
results.
A commercially
pure grade o f benzene was
by t h e N i c h o l s C h e m i c a l Company.
shaking a mixture
of benzene and
i n a large separating funnel.
w i t h new
Thiophene was
concentrated
The
supplied
removed by
sulfuric acid
o p e r a t i o n was
repeated
p o r t i o n s of a c i d u n t i l no t h i o p h e n e d i s c o l o r a t i o n
appeared.
The
w a t e r i f i t was
concentrated
present.
a c i d would a l s o remove most o f t h e
A f t e r c a r e f u l s e p a r a t i o n of the
a c i d l a y e r the thiophene-free
benzene was
placed i n a clean 2
d i s t i l l a t i o n f l a s k o v e r sodium r i b b o n and a l l o w e d t o s t a n d f o r
a day.
The t o p of the f l a s k was
closed with a drying funnel
of c a l c i u m o x i d e a l l o w i n g f r e e e v o l u t i o n o f hydrogen.
1.
19,
Distillation
f o r f i n a l p u r i f i c a t i o n was performed i n a packed
column o f 14 e q u i v a l e n t p l a t e s p r e v i o u s l y used f o r p u r i f i c a t i o n
purposes (19).
and d r i e d .
The column was c a r e f u l l y
Distillation
cleaned w i t h acetone
of the benzene was c a r r i e d
sodium a t a r e f l u x r a t i o o f 30:1.
out over
The i n i t i a l 200 ml. p o r t i o n
was d i s c a r d e d a f t e r which about 1 1. o f pure benzene o f b o i l i n g
p o i n t 80.4 °C was o b t a i n e d f o r t e s t i n g
The carbon t e t r a c h l o r i d e
purposes.
o b t a i n e d from the Baker and
Adamson Company was p u r i f i e d by d i s t i l l a t i o n o n l y .
at a r e f l u x r a t i o o f 30:1 gave carbon t e t r a c h l o r i d e
refractive
the
Distillation
of a
index t h a t checked f a v o u r a b l y w i t h t h a t g i v e n i n
literature.
Refractive indices
o b t a i n e d at 25°C were
1.4572 and 1.4980 f o r carbon t e t r a c h l o r i d e
respectively,
1.49794 ( 8 ) .
and benzene,
compared w i t h l i t e r a t u r e v a l u e s o f 1.45734 and
20.
PROCEDURE
(a) TBP S t i l l
The o p e r a t i o n o f t h e TBP s t i l l was e s s e n t i a l l y
the
same as t h a t o f any l a b o r a t o r y f r a c t i o n a t i n g u n i t .
A b a s i c d i f f e r e n c e , however, was t h a t two p r e s s u r e s
were used d u r i n g t h e d i s t i l l a t i o n o f c r u d e s : a t m o s p h e r i c
d i s t i l l a t i o n u n t i l t h e charge r e a c h e d a t e m p e r a t u r e o f
about
65O0F.
a f t e r which t h e column was c o o l e d , t h e n
10 mm. p r e s s u r e u n t i l t h e t e m p e r a t u r e a g a i n r e a c h e d
about 6$0°F.
the
Some comparable TBP s t i l l s f u r t h e r reduce
p r e s s u r e t o 1 mm. b u t s i n c e t h i s p a r t i c u l a r a p p a r a t u s
was n o t d e s i g n e d f o r such l o w p r e s s u r e s , t h e d i s t i l l a t i o n
was t e r m i n a t e d a t 10 mm.
To b e g i n o p e r a t i o n s a t a t m o s p h e r i c p r e s s u r e , a f t e r
the
s t i l l - p o t was charggd and a t t a c h e d t o t h e column,
c o o l i n g w a t e r was passed t h r o u g h t h e condensers,
powdered d r y - i c e p l a c e d i n t h e c o l d t r a p and t h e g l a s - c o l
h e a t e r was t u r n e d on. A normal procedure i n t h e o p e r a t i o n
of packed columns i s t o p r e f l o o d t h e column b e f o r e t h e
a c t u a l d i s t i l l a t i o n b e g i n s ; t h e purpose o f t h i s i s t o
c o m p l e t e l y wet t h e p a c k i n g s u r f a c e t o ensure maximum
column e f f i c i e n c y .
F o r two r e a s o n s t h i s p r o c e d u r e was
not f o l l o w e d : t h e l i q u i d - d i v i d i n g s t i l l - h e a d has t o o
s m a l l a c a p a c i t y t o cause column f l o o d i n g and i s i t s e l f
flooded f i r s t .
A l s o , i f f l o o d i n g was even
approached
21.
d u r i n g the i n i t i a l r e f l u x i n g o f a crude, too l a r g e a f r a c t i o n
would be l o s t t o the
cold trap.
slow r a t e of r e f l u x i n g , 1500
p e r m i t t e d t h r o u g h o u t the
As a r e s u l t , the
normal
t o 2000 ml. per h o u r ,
complete d i s t i l l a t i o n ;
l o s s i n i n i t i a l column e f f i c i e n c y was
was
the
possible
c o n s i d e r e d to be
not
significant.
A preliminary
h o u r was
equilibrium period
a l l o w e d b e f o r e any
receiver.
o f about h a l f
d i s t i l l a t e was
drawn i n t o
set t o g i v e a r e f l u x - r a t i o o f 10:1.
d i s t i l l a t e volume and
r e c e i v e r s t o p c o c k , and
inlet
t h e n d r a i n i n g the d i s t i l l a t e i n t o a
ml. graduated c y l i n d e r .
The
still-pot
temperature
To o b t a i n the i n i t i a l c o r r e c t volume
was
The
not i t s e l f added t o
d i s t i l l a t e i n t h e graduate because of i t s h i g h
discarded.
collected
added t o the g r a d u a t e d c y l i n d e r .
l i g h t f r a c t i o n , as much as 40 ml.,
but was
was
distilled
r e a d i n g , a volume of naphtha c o r r e s p o n d i n g t o t h a t
i n the c o l d t r a p , was
The
c o r r e s p o n d i n g v a p o r t e m p e r a t u r e were
o b t a i n e d by r e a d i n g t h e thermometer, c l o s i n g t h e
a l s o noted.
the
A f t e r t h i s time a t the normal r e f l u x i n g r a t e ,
the r e f l u x - t i m e r was
250
an
the
volatility,
Subsequent r e a d i n g s , t a k e n a t approximate
volume i n t e r v a l s o f 100
ml. d i d not need f u r t h e r
A f a l l i n g - o f f of the
d i s t i l l a t i o n r a t e due
f i c i e n t heat i n p u t t o the s t i l l - p o t was
o b s e r v e d by
the number o f drops f a l l i n g i n t o the d i s t i l l a t e
during a receiving period.
correction.
The
to
insuf-
counting
receiver
g l a s - c o l heater input
was
a c c o r d i n g l y a d j u s t e d . When the r e f l u x t e m p e r a t u r e r e a c h e d
o
about 250 F., the column and s t i l l - h e a d r i b b o n h e a t e r s were
22.
t u r n e d on.
The temperature o f t h e r i b b o n h e a t e r a t t h e
s t i l l - h e a d was m a i n t a i n e d a t about 30°F. below t h e v a p o r
temperature as i n d i c a t e d by a thermometer
the
heater.
placed inside
An i d e n t i c a l e l e c t r i c a l i n p u t was s u p p l i e d
t o t h e column r i b b o n h e a t e r ; t h e e x t e r n a l temperature o f
the
column, a l t h o u g h undetermined, would be somewhat h i g h e r
because o f t h e e x t r a i n s u l a t i o n c o v e r i n g t h e h e a t e r .
There
was l i t t l e danger o f d i s r u p t i n g t h e column o p e r a t i o n by
s u p p l y i n g t o o much heat by means o f t h e r i b b o n h e a t e r s s i n c e
b o t h t h e s t i l l - h e a d and column were vacuum-jacketed;
moreover,
at h i g h temperature o p e r a t i o n , t h e h e a t e r s and i n s u l a t i o n
were e s s e n t i a l i n r e d u c i n g heat l o s s e s s u f f i c i e n t l y f o r
normal d i s t i l l a t i o n .
A f t e r t h e system was e v a c u a t e d t o 10 mm.,
and t h e
manostat a d j u s t e d , d i s t i l l a t i o n a t t h e reduced p r e s s u r e was
performed i n t h e same way as a t a t m o s p h e r i c pressure.. To
measure d i s t i l l a t e volumes, however, was a problem.
When
a c o n v e n i e h t t volume, a g a i n about 100 m l . , was c o l l e c t e d
i n t h e r e c e i v e r , t h e vapor and s t i l l - p o t t e m p e r a t u r e s were
r e a d and t h e r e c e i v e r i n l e t and e v a c u a t i n g l i n e s t o p c o c k s
were c l o s e d .
The r e c e i v e r was t h u s i s o l a t e d f r o m t h e r e s t
of t h e u n i t ; a i r c o u l d be v e n t e d i n t o i t , t h e d i s t i l l a t e
d r a i n e d , and volume measured w i t h o u t d i s r u p t i n g t h e column
operation.
To a g a i n evacuate t h e c l o s e d and t h e r e c e i v e r
e v a c u a t e d , a l s o w i t h o u t d i s r u p t i n g t h e column
operation.
T h i s method r e q u i r e d t h e r e a d j u s t m e n t o f t h e manostat
time t h e d i s t i l l a t e volume was measured.
each
A n o t h e r method w h i c h
e l i m i n a t e d t h e r e a d j u s t m e n t o f t h e manostat was t o evacuate
COX CHART FOR TBP
EXTRAPOLATION
24.
the
r e c e i v e r w i t h an a u x i l i a r y vacuum pump.
To o b t a i n t h e complete TBP c u r v e a t a t m o s p h e r i c
p r e s s u r e , t h e t e m p e r a t u r e s o f t h e 10 mm. d i s t i l l a t i o n were
e x t r a p o l a t e d by means o f an e n l a r g e d Cox c h a r t (5) as shown
i n reduced s i z e i n F i g u r e 4«
T h i s c h a r t was c o n s t r u c t e d i n
- t h e u s u a l way and the f o c a l p o i n t d e t e r m i n e d u s i n g v a p o r
p r e s s u r e v a l u e s from t h e l i t e r a t u r e f o r s e v e r a l normal
hydrocarbons ( 1 8 ) .
E x t r a p o l a t i o n gave temperature v a l u e s
c o n s i s t e n t w i t h the a t m o s p h e r i c d a t a when p l o t t e d on a
g r a p h o f temperature v e r s u s volume p e r c e n t .
F o r example,
t e m p e r a t u r e s o f 350oF. and 400°F. a t 10 mm. gave c o r r e s ponding e x t r a p o l a t e d v a l u e s o f 6l5°F. and 670°F. a t 760
mm.
pressure; (the p r e c i s i o n o f the e x t r a p o l a t e d temperatures
d e c r e a s e d t o about £5°F. a t h i g h t e m p e r a t u r e s due t o t h e
condensed t e m p e r a t u r e s c a l e o f t h e Cox c h a r t . )
I n t h i s way,
d a t a f o r TBP c u r v e s , complete t o a t e m p e r a t u r e o f about 300°F.,
were computed.
(b) EFV S t i l l
The procedure f o l l o w e d f o r t h e EFV d e t e r m i n a t i o n s
was e s s e n t i a l l y as p r e s c r i b e d by Othmer e t , a l . ( 1 5 ) •
Both atmospheric and reduced p r e s s u r e d i s t i l l a t i o n s
c a r r i e d out by t h e same method.
were
Preliminary preparations
c o n s i s t e d o f p l a c i n g d r y - i c e i n t o t h e c o l d t r a p and s t a r t i n g
the
c o o l i n g - w a t e r through t h e condensers.
The s t i l l was
charged t h r o u g h t h e thermometer w e l l , a f t e r w h i c h t h e system
was evacuated t o t h e d e s i r e d o p e r a t i n g p r e s s u r e .
Heat was
25.
s u p p l i e d t o t h e s t i l l - p o t and vapor-arm, the vapor-arm b e i n g
kept a t a t e m p e r a t u r e about
i n i t i a l boiling point.
30OF.
h i g h e r than the expected
The temperature o f t h e
initial
b o i l i n g p o i n t corresponded t o the f i f t h drop o f d i s t i l l a t e
f a l l i n g i n t o the d i s t i l l a t e
(as suggested by Othmer e t , a l . ) ;
the c o r r e s p o n d i n g volume measurement wan not t a k e n as
zero,
but as t h e volume o f t h e l i g h t f r a c t i o n s c o l l e c t e d i n t h e
cold trap.
To h e l p i n making t h e r e c y c l e c o n t r o l e f f e c t i v e a p o i n t e r
was a t t a c h e d t o the end of t h e s t o p c o c k so t h a t t h e p r o p e r
p o s i t i o n c o u l d be r e a d i l y a t t a i n e d as shown by a c i r c u l a r
scale.
F u r t h e r m o r e , t h e r e c y c l e stream was
vaporized
partially
by means o f t h e r e c y c l e h e a t e r so t h a t i n t e r m i t t e n t
bubble's p a s s e d t h r o u g h the s t o p c o c k .
The b u b b l e s a i d e d i n
e s t i m a t i n g t h e r a t e o f r e c y c l e as w e l l as p r e v e n t e d s u p e r h e a t i n g o f t h e charge i n t h e s t i l l - p o t .
The volume i n the r e s e r v o i r was i n c r e a s e d
i n c r e a s i n g the s t i l l - p o t h e a t e r .
E q u i l i b r i u m was
by
established
when t h e d i s t i l l a t e was o f t h e same c o m p o s i t i o n as t h e vapor
i n e q u i l i b r i u m w i t h the l i q u i d
charge.
To a c c o m p l i s h t h i s
the l i q u i d temperature was kept c o n s t a n t r a t h e r than t h e
d i s t i l l a t e volume as suggested by Othmer e t a l . I n t h i s
s m a l l temperature changes c o u l d be n o t i c e d and heat
way
supplied
a c c o r d i n g l y , whereas s m a l l volume changes c o u l d n o t be
n o t i c e d soon enough t o p e r m i t easy c o r r e c t i v e a d j u s t m e n t .
A f t e r normal d i s t i l l a t i o n and r e c y c l e r a t e s o f about 120 drops
26.
p e r hour were e s t a b l i s h e d , t h e o n l y c o n t r o l n e c e s s a r y was
the heat i n p u t t o t h e s t i l l ; t h e r e c y c l e s t o p c o c k was kept
i n t h e same p o s i t i o n t h r o u g h o u t t h e d i s t i l l a t i o n .
For
o b t a i n i n g i n c r e a s e d volumes o f d i s t i l l a t e , t h e s t i l l
temperature
was s l o w l y i n c r e a s e d i n i n c r e m e n t s o f about 50°F., w i t h a
c o r r e s p o n d i n g i n c r e a s e i n vapor-arm t e m p e r a t u r e .
As t h e
temperature i n c r e a s e d t h e d i s t i l l a t i o n
increase
r a t e would
w i t h r e s u l t i n g h i g h e r volumes o f d i s t i l l a t e .
Equilibrium
was assumed when no volume change was observed o v e r a
p e r i o d o f about i hour a t a c o n s t a n t
s t i l l temperature, the
complete t i m e f o r a s i n g l e measurement t a k i n g up t o 4 h o u r s .
S i n c e t h e whole d e t e r m i n a t i o n c o u l d n o t be made i n
one e i g h t hour day, t h e d i s t i l l a t i o n had t o be d i s c o n t i n u e d
b e f o r e i t was completed.
To p e r m i t easy s t a r t - u p n e x t day,
the r e c y c l e s t o p c o c k was c l o s e d t r a p p i n g t h e d i s t i l l a t e i n
t h e r e s e r v o i r . The vacuum l i n e a l s o was c l o s e d w i t h a p i n c h cock ( d u r i n g reduced p r e s s u r e d i s t i l l a t i o n ) .
The f o l l o w i n g
day t h e d i s t i l l a t i o n c o u l d be c o n v e n i e n t l y c o n t i n u e d a t a
temperature a n o t h e r i n c r e m e n t above t h e one used p r e v i o u s l y .
The volume i n t h e c o l d t r a p was checked f o r l o s s due t o
evaporation.
The f l a s h c u r v e s a t e i t h e r a t m o s p h e r i c o r 10 mm.
pressure
c o u l d be drawn d i r e c t l y from the d a t a f o r t h e l i q u i d
t e m p e r a t u r e and t h e c o r r e c t e d volume o f d i s t i l l a t e .
27.
( c ) C a l i b r a t i o n o f Column
The t h e o r e t i c a l p l a t e
was
e f f i c i e n c y o f t h e TBP
column
checked by r e f l u x i n g a t t o t a l r e f l u x a m i x t u r e of the
p u r i f i e d benzene and c a r b o n t e t r a c h l o r i d e .
A charge o f about
2 1. o f 20 mole p e r c e n t carbon t e t r a c h l o r i d e
was
f o r two h o u r s , t h e n s m a l l samples o f t h e overhead
pot m i x t u r d s were t a k e n .
These were a n a l y z e d by
i n d e x a f t e r which r e f l u x i n g was
refluxed
and
still-
refractive
continued f o r another three
hours t o ensure t h a t e q u i l i b r i u m
had been a t t a i n e d .
Second
samples drawn gave t h e same r e f r a c t i v e i n d e x v a l u e s as t h e
first.
The r e f r a c t i v e i n d e x v a l u e s a t 2 5 ° C f o r t h e
still-
pot c o m p o s i t i o n and overhead were 1.4916 and 1.4783, r e s pectively.
The r e f r a c t i v e i n d e x - c o m p o s i t i o n r e l a t i o n s h i p
was
t h a t recommended by t h e U.S.
Bureau o f Mines (20) and
the
benzene-carbon t e t r a c h l o r i d e
vapor-liquid
data
were o b t a i n e d from t h e I n t e r n a t i o n a l
equilibrium
C r i t i c a l Tables ( 7 ) .
The p l a t e e f f i c i e n c y o f t h e column was
determined by
u s u a l McCabe and T h i e l e method (10) u s i n g an e n l a r g e d
l i q u i d equilibrium
method was
11.4
diagram.
the
vapor-
The v a l u e o b t a i n e d by t h i s
equivalent theoretical plates
f o r a column
of 22 i n c h e s of p a c k i n g i n c l u d i n g t h e s t i l l i - p o t * and
head as i l l u s t r a t e d i n F i g u r e $.
still-
29.
VI. RESULTS
F o r each o f t h e crude o i l s t e s t e d , t h r e e c h a r a c t e r i s t i c c u r v e s were d e t e r m i n e d : t h e a t m o s p h e r i c TBP,
^ . a t m o s p h e r i c EFV, and t h e 10 mm.
EFV c u r v e s .
The c u r v e s
are a l l p l o t t e d w i t h t h e volume p e r c e n t as a b s c i s s a and
temperature as o r d i n a t e .
F i g u r e s 8 a - 8h show t h e
a t m o s p h e r i c TBP and EFV c u r v e s ; t h e n u m e r i c a l d a t a appear
i n liable I .
The EFV c u r v e s a t 10 mm.
and a t m o s p h e r i c
p r e s s u r e appear i n F i g u r e s l O a - l O h .
The r e l a t i o n s h i p between t h e a t m o s p h e r i c TBP and
EFV 50 p e r c e n t b o i l i n g p o i n t s can be approximated by a
straight l i n e .
The d a t a p o i n t s a r e g i v e n i n SEable I I and
shown g r a p h i c a l l y i n F i g u r e 6 w i t h t h e b e s t s t r a i g h t
f i t t e d by t h e method o f l e a s t s q u a r e s .
line
The d o t t e d l i n e
c o r r e s p o n d s t o t h e c a l c u l a t e d r e s u l t s of Okamoto and Van
W i n k l e (14) f o r m i x t u r e s o f pure hydrocarbons
assuming
i d e a l behaviour.
I f t h e EFV curve i s assumed t o be n e a r l y a s t r a i g h t
l i n e , t h e n a s l o p e and t h e 50 p e r c e n t p o i n t would c h a r a c t e r ize i t .
An i n s p e c t i o n o f t h e TBP and EFV s l o p e s i n d i c a t e s
t h a t an a p p r o x i m a t e l y c o n s t a n t s l o p e d i f f e r e n c e between
the two c u r v e s e x i s t s .
The average s l o p e d i f f e r e n c e i s
c a l c u l a t e d t o be 3.511
-0.271 degrees p e r volume p e r c e n t
where 0.271 i s t h e p r e c i s i o n .
The v a l u e 3.511 i s s u b t r a c t e d
f r o m t h e TBP s l o p e g i v i n g t h e s l o p e o f t h e p r e d i c t e d EFV
curve.
The c o n s t a n t s l o p e d i f f e r e n c e i s r e p r e s e n t e d by a
30.
CORRELATION
450
OF T B P a
500
X =. EFV
EFV 5 0 %
BOILING
550
50 PERCENT
FIG. 6
BOILING
600
POINT
° F.
POINTS
650
COMPARISON
OF
SLOPE
CORRELATIONS
FIG. 7
32.
LEDUC-WOODB'END
CRUDE
JOSEPH
0 I
0
1
1
20
VOLUME
LAKE
1
CRUDE
1
40
PERCENT
FIG. 8 b
1
1
60
1
1
80
J
100
34.
TEXAS PIPELINE CRUDE
0
20
VOLUME
40
PERCENT
FIG.8C
60
80
100
35
PEMBINA
o»
0
i
1
20
V O L U M E
CRUDE
1
1
40
P E R C E N T
FIG.8d
1
1
60
1
1—
80
J
1
100
WIZARD
LAKE
CRUDE
37.
REDWATER
CRUDE
1
j
A.
F o r atmosj>heric p r e s s u r e
f
800
1
\
i
/
1
/
600
1
i
1
1
r
^ ^ ^ ^
1
O
1
1
//
• 400
ut
or
<
CC
/
Ul
Q.
•
/
1
i
UJ
1
200
•
—
— •
. 1
20
VOLUME
40
PERCENT
FIG. 8f
60
80
i
100
STETTLER
CRUDE
GOLDEN
SPIKE
CRUDE
40.
45 degree l i n e on a p l o t o f EFV s l o p e as o r d i n a t e and TBP
s l o p e as a b s c i s s a .
T h i s p l o t i s g i v e n by Okamoto and
Van W i n k l e as c a l c u l a t e d f o r t h e hydrocarbon
i s reproduced
mixtures.
It
i n F i g u r e 7 showing t h e d a t a p o i n t s , a l s o
l i s t e d i n Table I I , f o r the crudes.
I n c l u d e d on t h i s
p l o t i s a c o r r e l a t i o n o f the TBP and EFV s l o p e s p r o p o s e d
by N e l s o n and Harvey determined
from d a t a on p e t r o l e u m
fractions (12).
The a p p l i c a t i o n o f t h e proposed c o r r e l a t i o n s i s
i n d i c a t e d i n F i g u r e s 8a - 8h.
The a t m o s p h e r i c
TBP and EFV
e x p e r i m e n t a l c u r v e s as w e l l as t h e p r e d i c t e d c u r v e s , t h e
d o t t e d l i n e s , a r e shown f o r each c r u d e .
The p r e d i c t e d
curves show t h e b e s t a c c u r a c y i n t h e r e g i o n 10-60 volume
percent.
Phase d i a g r a m s , c o n s t r u c t e d f r o m t h e EFV d a t a a t
atmospheric
and 10 mm. p r e s s u r e s , a r e shown i n F i g u r e 9.
The 20 and 60 p e r c e n t v a p o r i z e d v a l u e s were chosen as b e i n g
most a c c u r a t e and c o n v e n i e n t f o r d e t e r m i n i n g t h e f o c a l
p o i n t s of t h e v a r i o u s c r u d e s .
No f u n c t i o n o f e i t h e r t h e
TBP o r EFV c u r v e s was found t o c o r r e s p o n d t o t h e r e l a t i o n
between t h e f o c a l p o i n t s and, as a r e s u l t , no c o r r e l a t i o n
i s g i v e n f o r l o c a t i n g them.
I t i s e v i d e n t t h a t i f some means
were a v a i l a b l e f o r l o c a t i n g t h e f o c a l p o i n t s t h e n an EFV
curve a t one p r e s s u r e would determine
pressure.
F o r comparison,
i t f o r any o t h e r
the f o c a l point f o r a petroleum
s t o c k , s t o c k I , i s g i v e n as determined
by Okamoto and Van
PHASE
DIAGRAM
FIG. 9
10
A
GOLDEN
SPIKE
0
TEXACO
PIPELINE
V
JOSEPH
LAKE
<D
STETTLER
•
WIZARD
10'
io
LAKE
"f
PEMBINA
ED
REDWATER
O
W00DBEND-LEDUC
UJ
_J
<
o
CO
®
CD
O
-
>-IO
or
STOCK
I
5
O
cr
UJ
UJ
- m m - ®
CO
UJ
or
10
•
i r
i—|—i I I i j i i i i j I i i i | i 111 j
1
200
400
600
TEMPERATURE
F , RECIPROCAL
SCALE
0
]—p
1000
1500
42
Winkle (13).
This f o c a l p o i n t i s only s l i g h t l y s h i f t e d
f o r a s e r i e s of stocks of d i f f e r e n t weights.
An attempt was made t o u t i l i z e t h e U.O.P. c h a r a c t e r i z a t i o n f a c t o r , K, fbr
method (22)
c o r r e l a t i n g purposes.
Maxwell's
was used i n d e t e r m i n i n g K from t h e 2 0 , 5 0 ,
and
80 p e r c e n t TBP t e m p e r a t u r e s , t h e TBP s l o p e , and t h e API
g r a v i t y f o r each c r u d e .
The K v a l u e s determined'ranged
from 1 1 . 6 0 t o 31.90 w i t h no a p p a r e n t r e l a t i o n t o t h e o t h e r
variables
correlated.
JOSEPH
LAKE
EFV
PEMB INA
EFV
47.
WIZARD
LAKE
EFV
48.
REDWATER
EFV
r
800
20
PERCENT
40
VAPORIZED
FIG. lOf
60
80
100
STETTLER
EFV
50.
WOODBEND-LEDKC
EFV
800
0
20'
PERCENT
40
VAPORIZED
FIG. lOh
60
80
100
51.
TABLE i :
WIZARD LAKE
TBP
Temp. OF
93
124
165
190
203
237
279
336
397
457
487
£
586
650
719
760
EFV
Vol. %
1.7
3.8
6.1
9.6
11.3
15.1
20.1
. 26.0
32.2
38.6
41.7
(ATM)
Temp. °F V o l .
152
248
288
325
363
392
457
522
583
653
680
1.0
6.0
12.0
17.0
24.0
28.0
39.0
49.0
58.0
67.0
70.0
EFV
10 (MM)
Temp. OF
Vol. %
16.2
20.2
33.2
45.2
53.2
62.2
76.2
179
203
280
343
405
457
588
51.7
28.2
65.2
68.3
± extrapolated
TEXAS PIPELINE
TBP
Temp. °F
EFV
Vol. %
104
122
157
187
213
257
295
338
372
12.0
17.5
21.9
26.1
32.1
33.5
427
472
544
601
670
726
760
41.6
48.1
54.6
61.1
68.5
73.4
77.0
A
4.5
6.0
8.4
ft e x t r a p o l a t e d
(ATM)
Temp. °F
133
-216
244
261
279
313
.372
426
442
491
531
563
615
Vol. f
1.0
6.0
7.0
11.0
15.0
21.0
32.0
41.0
44.0
< '53.0
59.0
64.O
72.0
EFH 10 (MM)
Temp. °F
172
183
. 205
215
270
327
387
442
447
Vol. %
15.0
18.0
22.0
24.0
34.0
45.0
55.0
63.0
67.0
52.
JOSEPH LAKE
TBP
Temp. °F
108
124
183
200
225
EFV
Vol. %
1.2
1.9
4.7
6.7
9.6
261
318
358
14.6
429
471
544
587
32.7
37.7
44.5
50.6
704
778
70.8
ft
644
20.9
26.6
(ATM)
EFV
•femp.oF' V o l . $
0.2
4.0
5.6
6.6
208
286
293
302
10.6
322
14.6
22.6
31.6
42.6
53.6
63.6
72.6
340
385
437
498
558
615
673
Temp. OF
158
226
306
345
394
417
484
10 (MM)
Vol. %
10.8
24.8
38.8
45.8
55.8
59.8
70.8
57.0
64.I
4 extrapolated
PEMBINA
TBP
Temp. °F
93
122
.145
196
252
297
354
414
468
507
ft
566
628
691
772
EFV
Vol. %
1.6
2.8
4.0
8.4
14.8
20.0
25.7
30.6
36.0
40.9
45.4
51.9
58.3
66.0
ft e x t r a p o l a t e d
(ATM)
Temp. °F
158
262
270
284
290
333
379
455
520
581
646
682
EFV
V o l . $>.
0.6
6.0
8.0
10.0
12.0
18.0
25.0.
36.0
46.O
56.0
64.O
69.0
(10 MM)
Temp. °F
Vol. %
189
15.4
18.4
30.4
40.4
214
286
349
405
484
540
591
48.4
60.4
67.0
73.0
53.
REDWATER
TBP
Temp, °F
EFV
Vol. $
81
133
160
189
214
280
338
385
424
2.3
4.7
6.1
8.2
11.5
19.8
25.0
29.5
32.8
466
523
618
662
714
752
35.3
42.3
50.6
55.4
60.3
66.0
ft
EFV
Temp. °F
Vol. $
151
261
273
298
343
388
457
529
579
631
669
0.6
7.0
8.0
12.0
19.0
26.0
37.0
48.0
56.0
63.0
69.0
r'
•
(ATM)-
Temp. °F
(10 MM)
Vol. %
22.0
27.0
36.0
43.0
47.0
52.0
60.0
65.0
66.0
72.0
215
243
293
334
359
381
429
477
489
554
o
ft e x t r a p o l a t e d
LEDUC-WOODBEND
TBP
Temp. °F
EFV
Vol. $
97
HI
142
^
2.3
3.9
198
io.O
&
\l\
263
307
2011
24.8
401
35.g
484
45.0
5?6
51.0
56.5
Ilk
711
711
'
70.1
6
4
5
ft e x t r a p o l a t e d
(ATM)
Temp. °F
Vol. %
153
230
246
279
300
0.6
4.0
6.2
12.2
17.2
23.2
31.2
40.2
52.4
61.6
68.6
77.6
...
3
2
?
370
423
487
554
603
669
EFV
Temp. °F
185
216
250
325
392
482
572
(10
MM)
Vol. %
11.6
19.6
26.6
42.6
53.6
66.0
77.0
54.
SOLDEN SPIKE
EFV (ATM)
TBP
Temp. °F
102
111
138
174
226
255
298
322
365
ft
441
492
520
576
651
696
744
Vol. %
2.2
3.3
4.7
8.1
13.8
19.1
24.0
26.8
31.6
39.9
44.9
48.3
54.6
63.1
68.3
73.3
EFV (10 MM)
Temp. ° F
Vol. $
Temp. ° F
Vol. %
153
2.0
6.0
10.0
, 15.0
22.0
31.0
37.0
46.0
172 °
190
11.0
14.0
30.0
30.0
41.0
50.0
57.0
63.0
235
264
290
329
378
414
459
502
541
574
617
646
680
52.0
223
273
336
392
442
487
58.0
64.O
70.0
73.0
76.0
.
ft extrapolated
STETTLER
EFV (ATM!
TBP
Temp. ° F
127
162 ,
225
252
332
392
3.3
6.2
10.4
13.7
19.5
24.6
487
538
570
598
658
712
752
800
31.7
36.1
39.5
43.2
48.1
53.5
58.6
62.7
ft
Vol. %
Vol. %
ft extrapolated
192
III
351
425
498
563
629
680
1.0
5.0
7.0
12.0
22.0
33.0
42.0
51.0
57.0
EFV (10 MM)
Temp. ° F
255
343
399
471
525
586
649
Vol. %
19.4
32.4
39.4
49.4
57.0
64.O
70.0
TABLE I I
SAMPLE
TBP
50% p o i n t ° F s l o p e T / V o l $
-
f
EFV
P r e d i c t e d EFV
50% point°F slope'F/vol.^ 5<$ point °F s l o p e °F/Vol. %
ft
t
Texas P i p e l i n e
503
8.93
477
5.70
464
5.42
Golden S p i k e
534
9.10
490
5.83
491
5.59
Woodbend-Leduc
527
8.83
475
5.63
485
5.32
Joseph Lake
584
9.10
540
5.63
535
5.59
Pembina
610
.10.33
546
6.67
557
6.82
W i z a r d Lake
571
9.77
531
6.47
523
6.26
Redwater
604
10.80
541
6.47
552
7.29
Stettler
678
10.80
621
7.17
616
7.29
ft average d e v i a t i o n o f 50 p e r c e n t p o i n t =
8.1°F
56.
VII.DISCUSSION OF RESULTS
E m p i r i c a l c o r r e l a t i o n s r e q u i r e a s u f f i c i e n t amount
o f d a t a t o a d e q u a t e l y r e p r e s e n t t h e complete
variables.
range o f
This i s d e f i n i t e l y a l i m i t a t i o n w i t h c o r r e l a t i o n s
f o r A l b e r t a crude o i l s ; a l t h o u g h TBP d a t a a r e more e a s i l y
a v a i l a b l e , both TBP and t h e c o r r e s p o n d i n g EFV d a t a i n
a d d i t i o n t o t h o s e g i v e n here a r e almost n o n - e x i s t e n t .
The
c h a r t s r e s u l t i n g from t h e t e s t s on t h e e i g h t A l b e r t a crudes
a r e , t h e r e f o r e , somewhat l i m i t e d i n t h e i r v a l u e as
correlations.
The c u r v e s o b t a i n e d f o r t h e i n d i v i d u a l
samples,
however, c o u l d be u s e f u l i n d e s i g n c a l c u l a t i o n s .
The c o r r e l a t i o n o f t h e TBP and EFV 50 p e r c e n t
boiling
p o i n t s g i v e n here adds weight t o t h a t o f Okamoto and Van
Winkle.
I t s h o u l d be noted t h a t t h e i r 50 p e r c e n t p o i n t s
a r e n o t e x p e r i m e n t a l l y determined b u t a r e c a l c u l a t e d f o r
m i x t u r e s o f pure hydrocarbons
s i m u l a t i n g petroleum
fractions.
P r o p e r t i e s o f t h e components a r e a v a i l a b l e f o r t h e s e
c a l c u l a t i o n s , e s p e c i a l l y f o r t h e common hydrocarbons
b o i l i n g range used by Okamoto and Van W i n k l e
i n the
(150 t o 350°F).
When i t becomes e v i d e n t t h a t t h e TBP and EFV s l o p e p l o t i s
a l s o c o r r o b o r a t e d by a s i m i l a r p l o t f o r t h e c r u d e s , t h e
s i m i l a r i t y i s even more s i g n i f i c a n t .
T h i s approach
t o the
c h a r a c t e r i z a t i o n curves o f crude o i l s may prove t o be more
u s e f u l t h a n i the reference t o petroleum f r a c t i o n s , t h e
u s u a l method
adopted.
The a c c u r a c y o f t h e EFV 50 p e r c e n t p o i n t determined
57.
by t h e Okamoto and Van W i n k l e method i s good when compared
w i t h t h a t o b t a i n e d f o r t h e b e s t A.S.T.M. - EFV c o r r e l a t i o n .
The c o r r e l a t i o n o f E d r a i s t e r and P o l l o c k (4) g i v e s t h e
s m a l l e s t mean d e v i a t i o n o f ±12.5°F. i n t h e p r e d i c t e d
flash
50 p e r c e n t p o i n t f o r p e t r o l e u m f r a c t i o n s o f a l l t h e c u r r e n t
a v a i l a b l e c o r r e l a t i o n s , as shown by Ghu and S t a f f e l ( 2 ) .
The l o w e r v a l u e o f - 8.1°F. was o b t a i n e d f o r t h e c r u d e s .
A l t h o u g h t h e A.S.T.M. d i s t i l l a t i o n s a r e somewhat l e s s
r e p r o d u c i b l e t h a n t h e TBP d i s t i l l a t i o n s , t h e r e l a t i v e l y s m a l l
mean d e v i a t i o n i s v e r y f a v o u r a b l e .
I n t h e i r s l o p e c o r r e l a t i o n Okamoto and Van W i n k l e
c a l c u l a t e d t h e 10-70 p e r c e n t s l o p e s f o r t h e h y d r o c a r b o n
mixtures.
T h i s i s a s l o p e commonly used i n s l o p e c o r r e l a t i o n s ;
however, s i n c e b o t h t h e TBP and EFV curves f o r c r u d e s a r e
s t r a i g h t o n l y f o r t h e 25-55 p e r c e n t range, t h e s e s l o p e s
were used i n p r e f e r e n c e .
Very l i t t l e
change i n s l o p e would
be observed i f t h e 10-30 p e r c e n t s l o p e was used as
suggested by E d m i s t e r and P o l l o c k (4). s i n c e t h e v a r i a t i o n
i n t h i s r e g i o n was o n l y s l i g h t .
A l t h o u g h t h e TBP s l o p e s
a r e a p p r o x i m a t e l y c o n s t a n t over the complete
range o f
10-70 p e r c e n t , t h e EFV s l o p e s have a pronounced c u r v e
upward i n t h e 55-70 p e r c e n t range.
The 25-55 p e r c e n t s l o p e s ,
t h e r e f o r e , a r e most c h a r a c t e r i s t i c .
The use o f a t m o s p h e r i c TBP and EFV d i s t i l l a t i o n s
i n s t e a d o f a t p r e c i s e l y 760 mm. p r e s s u r e may be q u e s t i o n e d .
V a r i a t i o n s i n a t m o s p h e r i c p r e s s u r e have been n o t e d from
58.
757
"to 760 mm. f o r t h e i n d i v i d u a l d e t e r m i n a t i o n s .
The
t e m p e r a t u r e adjustment c o r r e s p o n d i n g t o t h i s p r e s s u r e
v a r i a t i o n i s no more t h a n 2°F. a s e s t i m a t e d from t h e Cox
c h a r t and i s o f t h e o r d e r o f a c c u r a c y t h a t t h e Cox c h a r t
can be r e a d .
The u s u a l method i s t o n e g l e c t t h i s
temperature discrepancy.
small
The C a l i f o r n i a R e s e a r c h C o r p o r a t i o n
p u b l i c a t i o n (1) on t h e comprehensive a n a l y s i s o f Redwater
urude showed t h e TBP curve as o b t a i n e d a t a t m o s p h e r i c
p r e s s u r e (358 mm.) w i t h o u t c o r r e c t i o n .
S i m i l a r adjustment
o f t h e EFV d a t a w a s ' n e g l e c t e d f o r t h e same r e a s o n .
Chu
and S t a f f e l ( 2 ) , i n t h e i r r e c e n t s u r v e y o f t h e
c o r r e l a t i o n s o f A.S.T.M. and EFV c u r v e s gave an i n t e r e s t i n g
discussion
on t h e use o f the'U.O.P. c h a r a c t e r i z a t i o n
K, as a c o r r e l a t i n g v a r i a b l e .
factor,
The w r i t e r s agree t h a t the
K f a c t o r c o r r e c t i o n i s a p p l i e d t o t h e 50 p e r c e n t p o i n t o f
the p r e d i c t e d
f l a s h curve w i t h
some advantage i n such
c o r r e l a t i o n s as t h a t by E d m i s t e r and P o l l o c k
( 4 ) ; however,
t h e y doubt t h a t i t s use a c t u a l l y a c c o u n t s f o r t h e d i f f e r e n c e
i n aromaticity
of the f r a c t i o n s :
" I t i s assumed that t h e c h a r a c t e r i z a t i o n
f a c t o r would have a s much e f f e c t on any
p o i n t on t h e f l a s h c u r v e as i t does on
the 50 p e r c e n t p o i n t .
As i t does n o t
appear t o b e n e f i t t h e 10 and 70 p e r c e n t
p o i n t s some doubt i s c a s t on t h e v a l i d i t y
o f t h e c o r r e c t i o n by t h e c h a r a c t e r i z a t i o n
f a c t o r a t t h e 50 p e r c e n t p o i n t " ( 2 )
The a p p l i c a t i o n o f a K f a c t o r c o r r e c t i o n t o t h e TBP-EFV
c o r r e l a t i o n s would be l i k e w i s e c r i t i e i z e d .
59.
Some a s p e c t s o f t h e i n i t i a l d e t e r m i n a t i o n s o f
t h e TBP and EFV curves s h o u l d be f u r t h e r c o n s i d e r e d .
One
of t h e problems c o n c e r n i n g t h e TBP d i s t i l l a t i o n was t h e
method o f e x t e n d i n g the. second p o r t i o n o f t h e curve o b t a i n e d
at 10 mm. t o atmospheric p r e s s u r e .
The s t a n d a r d method
has heen t o f o l l o w t h e l i n e f o r t h e n - p a r a f f i n o f e q u a l
b o i l i n g p o i n t on a Cox c h a r t t o determine
atmospheric temperature.
the corresponding
A p o s s i b i l i t y f o r t e s t i n g the
v a l i d i t y o f t h i s method o f e x t r a p o l a t i o n appeared t o be a
complete TBP d i s t i l l a t i o n a t 10 mm. p r e s s u r e and t h e compari s o n w i t h one p a r t i a l l y completed
a t atmospheric
pressure.
When.: t h i s was attempted t h e q u a n t i t y o f condensate
removed by t h e d r y Q i c e t r a p was e x c e s s i v e making e v a c u a t i o n
t o 10 mm. i m p o s s i b l e .
Careful!,, r e f e r e n c e t o t h e Cox c h a r t
i n d i c a t e d t h a t a l l t h e l i g h t e s t f r a c t i o n s , up t o about 20
p e r c e n t would be v a p o r i z e d a t 10 mm. and a t room
The
reduced p r e s s u r e d i s t i l l a t i o n was u s u a l l y begun a t about
35 volume p e r c e n t .
was
temperature.
The o v e r l a p o f t h e two d i s t i l l a t i o n s
c o n s i d e r e d t o o s m a l l t o be s i g n i f i c a n t ; as a r e s u l t ,
t h e complete
10 mm. d i s t i l l a t i o n was abandoned.
No g r o s s
e r r o r i n the TBP curve i s p o s s i b l e , however, s i n c e t h e
e x t r a p o l a t e d p o r t i o n o f t h e curve f o l l o w s c o n s i s t e n t l y
from t h e i n i t i a l p a r t o f t h e c u r v e .
The a p p l i c a t i o n o f t h e Cox c h a r t f o r t h e e x t r a p o l a t i o n o f EFV curves has, q u i t e j u s t l y , r e c e i v e d more
criticism.
S i n c e t h e o i l f r a c t i o n s i n a TBP d i s t i l l a t i o n
60.
are r e l a t i v e l y narrow - f r a c t i o n s , i t i s l i k e l y t h a t t h e
assumption t h a t t h e y can be c h a r a c t e r i z e d by n - p a r a f f i n
hydrocarbons i s v a l i d .
I n t h e EFV d e t e r m i n a t i o n s t h e con-
densate volume i n c l u d e s components o f a wide b o i l i n g range;
the o b v i o u s p o s s i b l e e r r o r i s t h a t t h i s o i l f r a c t i o n does
not have t h e same c h e m i c a l c h a r a c t e r i s t i c s as t h e n - p a r a f f i n
o f t h e same b o i l i n g p o i n t .
The Cox c h a r t method f o r
e x t e n d i n g EFV d a t a t o h i g h p r e s s u r e s has been sh^mm t o be
i n e r r o r by E d m i s t e r and P o l l o c k (4) who a l s o p r e s e n t a
c o r r e l a t i o n s u i t a b l e f o r t h i s purpose.
pressures,
F o r subatmospheric
however, t h e Cox c h a r t i s g e n e r a l l y a c c e p t e d as
a c o n v e n i e n t and dependable means f o r e x t r a p o l a t i n g EFV
d a t a a v a i l a b l e a t two p r e s s u r e s .
S l i g h t l y l e s s dependable
i s the p l o t o f t h e l o g a r i t h m of the pressure versus t h e
r e c i p r o c a l t e m p e r a t u r e ( F i g u r e 9)5
however, i t a l s o i s
q u i t e adequate i n t h e l o w p r e s s u r e r e g i o n .
The f o c a l p o i n t s
f o r t h e c r u d e s , as shown on t h e l a t t e r p l o t , a r e l o c a t e d
a t p r e s s u r e s so f a r beyond t h e c r i t i c a l p r e s s u r e s o f
petroleum f r a c t i o n s that the question
significance.
of t h e a b s o l u t e
a r i s e s as t o t h e i r
The l o c a t i o n o f a f o c a l p o i n t i s a f u n c t i o n
v a l u e o f t h e 50 p e r c e n t p o i n t a t a t m o s p h e r i c
p r e s s u r e and t h e temperature d i f f e r e n c e o f t h e two 50 p e r c e n t
points.
F o c a l p o i n t s o f o t h e r c r u d e s would have t o be com-
p a r e d i n t h e l i g h t o f t h e s e two v a r i a b l e s b e f o r e any
conclusions
c o u l d be drawn.
61.
\
VIII.
BIBLIOGRAPHY
1 . C a l i f o r n i a R e s e a r c h C o r p o r a t i o , Richmond, C a l i f . ,
Report on Redwater Crude a n a l y s i s , F e b . 9 (1953)•
2. Chu, J . C , and S t a f f e l , E . J . ,
J , I n s t , o f P e t . , Ul 3 7 5 , 9,2 ( 1 9 5 5 ) .
t
3 . C o l l i n s , F.C., and Vernon, L.,
I n d . E n g . Chem., 1 8 , 673 ( 1 9 4 6 ) .
''
4 . E d m i s t e r , W. C , and P o l l o c k , D.H..
Chem. fing. p r o g . , ^
905 ( 1 9 4 8 ) .
5 . Cox, E.R.,
I n d Eng. Chem., 1£, 592 ( 1 9 2 3 ) .
6 . G i l m o n t , R.,
A n a l . Chem., 22,
157 ( 1 9 5 1 ) . ^
7. International C r i t i c a l Tables,
M c G r a w - H i l l Book Co., N.Y., 2> 3 0 9 ( 1 9 2 8 ) .
8. Ibid.,
2, 2 8 7 ,
(1928).
9 . K a t z , O.L., and Brown, G.G.,
I n d . E n g . Chem., 2 £ , 1278 ( 1 9 3 3 ) .
1 0 . McCabe, W.L., and T h i e l e , E.W.,
I n d . Eng. Chem., 12, 605 ( 1 9 2 5 ) .
1 1 . N e l s o n , W.L., and Sonders, M.,
J . P e t . Engr., 2> 1. 1 3 1 ( 1 9 3 1 ) .
1 2 . N e l s o n , W.L., and Harvey, R . J . ,
O i l Gas J o u r n a l , 22, June 1 7 ,
(1948).
1 3 . Okamoto, K.K., and Van W i n k l e , M.,
P e t . R e f i n e r , 8, 113 (1949).
14.
Ibid.,
1, 729
(1950).
15. Othmer, D.F., Ten E y c k , E.H., and T o l i n , S.,
I n d . E n g . Chem., £2, 1607 ( 1 9 5 1 ) .
1 6 . P a c k i e , J.W.,
T r a n s . Am. I n s t . Chem. E n g r s . , 2Z>-51 ( 1 9 4 9 ) .
1 7 . PiroomoV, R.S., and Beiswenger, G.A.,
P r o c . Am. P e t . I n s t . , 1 0 , 2 , S e c . I I , 52 ( 1 9 2 9 ) .
62.
18. Rubber C h e m i c a l Company,
Handbook o f P h y s i c a l a n d C h e m i s t r y , 2016; ( 1 9 5 3 ) .
19. W a l d i c h u k , M.,
M.A.Sc. T h e s i s , U.B.C., ( 1 9 5 0 ) .
20. Ward, A.L.,
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