riazi daubert 1980
TRANSCRIPT
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Ind Eng. Chem. Process
Des.
Dev. 1980, 79, 289-294
28s
a firm should or should not enter into the m anufacture of
an existing chemical.
T o use the proc edure , two pieces of information ar e
required: (1) he demand curve for the product;
(2)
es-
timates of the annual cost of manufacture. Using the
above information, eq 4a a nd 4b ar e solved simultaneously
an d a search over process unit sizes can be performed to
find the size that maximizes profit under each market
assumption (Cournot 's Implicit Collusion).
In this m anne r, a range of process un it sizes along with
estimates of mark et share, price, output, a nd profits can
be determin ed for the firms. Tables similar to Tables VI1
an d VI11 can also be prep ared which can serve the process
designer as quick, qualitative guides for the characteriza-
tion of firms' behavior on any specific chemical marke t th at
the firm may be considering entering.
By means of this procedure, more information is
available for the dec:ision-making process withou t the usual
assumptions t o estimate m arket shares an d production.
Furth erm ore, the rule-of-thumb procedures
so
common in
sett ing price are no t needed.
We ca nnot conclude from our studi es which of the two
assumptions, Implicit Collusion or Cournot's, describes
bet ter t he m ark et behavior of the oligopolistic firms in the
chemical process industr ies. Th e only way to test the
validity of the tw o assump tions would be to compare their
predictions with a ctual performance for a particular duo-
poly. To d o this, the total cost equation must be derivable
from th e process technical information and enough price
history mu st be available to estimate a dem and curve at
the time of decision. Th e equilibrium price and ind ustry
ou tpu t plus each firm's ma rket sha re could then be com-
pared w ith the actual situation . Of course, such a com-
parison assumes that the f irms behave in an optimal
fashion either by analysis or by experience.
Acknowledgment
The authors would like to acknowledge the financial
support provided by the Latin American Scholarship
Program of the A merican Universit ies (LASP AU), the
Chemical Engineering Department of the University of
Delaware, and the Universidad C atijlica Madre y Maes tra,
Santiago, Dominican Republic. Th e authors are also most
grateful for many helpful discussions with Professor Eri c
Brucke r, Dean, College of Business an d Econom ics of th e
University of Delaware.
Literature Cited
Bogaert,
R.,
M.ChE. Thesis, University of Delaware, Newark, DE, 1979.
Cohen, K . J.; Cyert, R. M Theory of the Firm: Resource Allocation in a Market
Leftwich,
R.
H. The Price System and Resource Allocation , 5th ed.; The
Miller, R.
L.
Intermediate Microeconomics , M&aw-Hill: New York, NY, 1978;
Von Neumann, J.; Magenstern, 0. Theory of
Games
and Economic Behavior ,
Wei, J.;
Russell,
T. W. F.; Swartzhnder, M. W. The Structure of the Chemical
Economy , Prentice-Hall: Englewocd Cliffs, NJ, 1965; p 138.
Dryden Press: Hinsdaie, IL, 1973; p 9.
p 293.
Princeton University Press: Princeton, NJ, 1953; Chapter 1.
Processing Industries , McGraw-Hill: New York, NY, 1979;
p
52.
Rece iv ed f o r reuiew June 26, 1979
Accep t ed
November
26, 1979
Predict ion of the Composit ion
of
Petroleum Fractions
Mohiammad
R.
Riazi and Thomas E. Dauber l
Department
o
Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
Based on t h e composition of defined hydrocarbon mixtures, an a ccura te, generalized method is proposed to predict
t h e firactional composition of paraffin s, naphthenes, and aromatics contained in both light and heavy petroleum
frac tion s. Viscosity, spec ific gravity, and refractive
index of t h e desired
fraction are
used
a s
input
parameters.
Introduction
In prediction of physical and thermodynam ic properties
of petroleum fractions
it
i s impor tan t to de termine the
proportion of paraffinic, naphthenic, and aromatic hy-
drocarbons present
in
the fraction (H uang and Daubert ,
1974; Riazi, 1979). Since the comp osition of petroleum
fractions is not usually experimentally determined, de-
velopment of a reliable metho d to es timate molecular type
analysis is qu ite necessary.
Many methods have been developed to predict the
percentage of paraffins, naphthen es, and aromatics in an
olefin-free petroleum fraction. Th e most common proce-
dures are the n d llf method and the refractivity-inter-
cept-density method The n d M method of Van Nes and
Van W esten (1951) fo r estim ating the percentage carbon
as aromatic, naphthenic, or paraff inic structure from
measured values of density, refractive index, sulfur content,
and molecular weight is a set of empirical equations at 20
or
70 C.
Th e refractivity-intercept-density meth od of Kurtz et
al. (1958) is a triangular graphical relation between per-
centage carbon as arom atic, naph thenic , or paraffinic;
refractivity intercept
( R J ;
nd density. Thi s method re-
quires tha t the arom atic percentage m ust be known.
A number of other procedures have been discussed in
various sources (Boelhower et al., 1954; Ku rtz e t al., 1958,
1936,1937; Van Nes and V an Westen, 1951; Waterman et
al., 1958). However, all of the existing metho ds are useful
only for high-boiling virgin fractions a nd are acc urate only
for data on which the m ethod is based. The main purpose
of this work was to develop a general meth od t o predict
mole fraction of paraffinic, naphthe nic, or arom atic com-
poun ds for light and heavy fract ions which is not based
on the composition of a certain group of petrole um frac-
tions.
Development
If
the mole fraction of paraffins, nap hthen es, an d aro-
matics for an olefin-free petroleum fraction are defined as
980 American Chemical Society
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290
Table
I.
Ind.
Eng.
Chem. Process Des. Dev., Vol.
19, No.
2, 1980
Values of Characterization Factors in Figure 1
value range
hydrocarbon type M Ri VGC K I
Daraffin 331-535 1.048-1.05 0.74-0.75 13.1 -13.5 0.267-0.27 3
Aapht hene
2
4 8-4 29
1.03-1.046
aromatic 180-395 1.07-1 lo 5
xp,x,, and x respectively, three expressions for prediction
of these thr ee unknowns can be developed. Th is requires
a set of three in depen dent equation s relating xp,
x
and
x,
to each other and some other known parameters. Th e
first equation is the obvious molar balance.
xp+ x,
+
x,
=
1
1)
Th us, two more equations are needed. In development of
these equations, it is necessary that properties of petroleum
fraction be related t o the p roper ties of each homologous
hydrocarbon g roup by a mixing rule, the simplest of which
is Kay’s rule. Therefore, at least two parameters are
needed to develop the two equations.
In order to predict t he composition of petroleum frac-
tions w ith reasonable accuracy, fractions are divided into
two molecular weight ranges-viscous fraction s (200
< M
<
500) and light fractions
( M
<
200). It should be noted
that these molecular weight range values are approximate
values.
1. Viscous
Fractions
Among different characteriza-
tion factors proposed in t he literature, refractivity intercept
(Ri) and viscosity gravity cons tant (VGC ) were chosen for
developm ent of the two equations to use with eq 1. In
selection of these two parameters, it was a t tempted to
choose a parameter which can best se parat e different ho-
mologous hydrocarbon groups. Refractivity interc ept
(Kurtz and Ward, 1936, 1937) is defined by
R i = n -
d
2
-
The VGC is defined by Hill and Coats (1928) as
1 0 s 1.0752 log (VI - 38)
(3)
(4)
in which Vl and V, are Say bolt universal viscosities at 100
an d 210 OF, respectively. Equ ation s 3 and 4 give ap-
proximately the same value for VGC of a given hydro-
carbon . Since in the ab ove equations viscosity is defined
as
Saybolt universal (SSV viscosity, therefore the y cannot
be used for light hydrocarbons (approximately M 180).
Figure 1and Table
I
show a comparison between Ri and
VGC with two other characterization factors: Watson
K
and a factor
I
proposed by Huang (1977). Parameter
I
is
a fun ction of only refractive index.
VGC
=
10 - log (V, 38)
S 0.24 0.022 log (V, 35.5)
0.755
GC =
n - 1
I = -
n
+
2
(5)
From Figure
1
it is obvious that R i and VGC separate
paraff ins, naphthenes, an d aromatics better th an either
of the o ther two parame ters. Also, Ri and VGC vary over
a small range when compared with
K
and
I .
This indicates
th at a single value for Ri, for instance , can characterize Ri
values for all paraffin s. Da ta on viscosity, refractive index,
and density of heavy hydrocarbons were taken from AP I
Research Project 42 (1962). For heavy
( M
> 200) hydro-
carbon s, average values of R i and VGC for each homolo-
gous hydro carbo n group were estimated . Values of 1.0482,
0.89-0.94
10.5-13.2 0.278-0.308
0.95-1.13 9.5-12.53 0.29 8-0.362
c 3 2 N
A
1
I
I I
I
I
I
I
I
I I
1 0 4 I
Ob
oa
I 0 2
R
1 A I
I I I I I I I I I I
0
9
I O 1 0 8
GC 1
0 7 o a 4
I N
I
A i El
K I
I
I I
I
I I
I I
I
I
9
10
12
13
I 4
1
I
lpl I
A
I
I L I I I I I I I I
1
0 2b
o
2a 0
30
0 32 0 34 0
36
Figure 1. Comparison of different characterization factors (see
Table
I).
1.038, an d 1.081 were obta ined for the average Ri of pa -
raffins, naphthene s, aro matics, while values of 0.744,0.915,
and 1.04 were obtained for the average VGC of paraffins,
naph thene s, and aromatics, respectively. By using Kay’s
mixing rule, Ri and VGC of an olefin-free petroleum
fraction can be obtained by the following equations
Ri = 1 . 0 4 8 2 ~ ~1 . 0 3 8 ~ ~1 . 0 8 1 ~ ~ (6)
VGC
=
0 . 7 4 4 ~ ~0 . 9 1 5 ~ ~1 . 0 4 ~ ~ (7)
A
regression of 33 defined hydrocarbon mixtures changes
the co nstants in these equations less than 2% . Various
compositions of these ternary systems were used-n-oc-
tadecane(P)-2-butyl-l-hexahydrindan(N)-2(ar),
-d i -
methyl-3-octyltetralin(A);n-octadecane(P)-1-a-decalyl-
pentadecane(N)-2(ar) ,
6-dimethyl-3-octyltetralin(A);
and
n-octadecane P)-9 -as-perhydroindacenylheptadecane-
(N)-11-a-naphthyl-10-heneicosene(A)-where , N , a n d
A refer to paraffin, naphthene, and aromatic, respectively.
After regression, eq 6 and 7 become
(8)
(9)
Ri and VGC equa tions together with eq
1
can then be
solved simultaneously to obtain equations for
xp,
x an d
x, which can then be used to predict the composition of
viscous fractions
( M
> 200)
if
Ri and VGC are
known.
Th e
final results after simultaneous solution of eq 1,8, an d 9
may be summarized as follows
(10)
(11)
(12)
2. Light Fractions As mentioned earlier for light
petroleum fractions the VGC canno t be calculated as de-
f ined by eq 3 and 4. I t was attempted t o define a new
Ri
=
1 . 0 4 8 6 ~ ~1 . 0 2 2 ~ ~1 . 1 1 ~ ~
VGC = 0 . 7 4 2 6 ~ ~0 . 9 ~ ~1 . 1 1 2 ~ ~
xP
=
9.00 + 12.53Ri 4.228VGC
X = 18.66 19.90Ri + 2.973VGC
X
= 8.66 + 7.37Ri
+
1.255VGC
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Ind. Eng. Chem. Process Des. Dev.,
Vol. 19,
No. 2,
1980
291
Table 11. Data on the Composition
of
Light Petroleum Fractions'
1
2
3
4
5
6
7
8
9
10
11
12
1 3
1 4
15
1 6
17
18
1 9
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
no.
M Tb d n S
0.7322 1.4 074 0.736502
131
144
120
142
162
227
214
126
129
162
127
157
171
1 5 3
127
1 3 3
130
127
162
132
1 6 1
130
126
166
161
137
130
166
137
1 3 3
127
1 3 3
165
1 5 4
165
157
160
137
1 3 3
130
170
196
28 2
321
260
32 2
404
547
535
297
306
39 7
298
385
417
385
29 7
315
30 4
29 5
39 2
303
40 5
312
30
0
406
397
329
307
40 5
329
316
297
317
40 3
37 2
40 3
38 5
39 2
329
318
307
41 7
0.77 33
0.8008
0.7358
0.7586
0.8045
0.8578
0.8433
0.7517
0.7701
0.799
0.769
0.801
0.810
0.786
0.7637
0.762
0.759
0.752
0.788
0.759
0.792
0.763
0.763
0.808
0.806
0.782
0.775
0.805
0.778
0.7740
0.77
0.767
0.786
0.779
0.797
0.7915
0.793
0.7756
0.7711
0.7671
0.799
1.4335
1.4436
1.4188
1.4260
1.4444
1.4776
1.4694
1.428
1.434
1.4463
1.433
1.447
1.45
1.444
1.4301
1.435
1.4325
1.427
1.449
1.424
1.45
1.4345
1.4343
1.4485
1.45
1.437
1.4352
1.448
1.437
1.4354
1.4328
1.4365
1.443
1.4398
1.4457
1.444
1.4442
1.4382
1.4356
1.4378
1.4464
0.7774
0.8046
0.7395
0.7624
0.8083
0.8616
0.847 5
0.7555
0.7740
0.803
0.7725
0.805
0.816
0.7899
0.7675
0.7658
0.7628
0.7558
0.792
0.7628
0.796
0.7668
0.7668
0.8121
0.8101
0.786
0.7789
0.809
0.7819
0.7779
0.77 39
0.7709
0.7899
0.7829
0.8
0.7955
0.797
0.7795
0.775
0.771
0.8025
composition
v210
X P Xn
X a
0.364 0.362 0.582 0.056
0.444
0.525
0.414
0.503
0.739
1.239
1.179
0.464
0.520
0.7
1
0.555
0.75
0.83
0.78
0.535
0.51
0.47
0.458
0.700
0.52
0.74
0.508
0.50
0.79
0.76
0.60
0.55
0.74
0.557
0.530
0.516
0.515
0.753
0.665
(1.43)
(1.27)
(1.33)
(0.92)
(0.87)
(0.83)
(1.55)
0.397
0.186
0.619
0.593
0.309
0.298
0.388
0.605
0.490
0.375
0.420
0.300
0.260
0.538
0.500
0.665
0.650
0.655
0.580
0.510
0.563
0.656
0.637
0.285
0.295
0.390
0.420
0.365
0.455
0.475
0.510
0.600
0.590
0.600
0.420
0.435
0.425
0.460
0.490
0.500
0.420
0.396
0.698
0.306
0.308
0.643
0.456
0.415
0.135
0.315
0.440
0.390
0.495
0.525
0.181
0.270
0.170
0.170
0.170
0.225
0.395
0.187
0.171
0.174
0.505
0.495
0.415
0.400
0.455
0.350
0.320
0.310
0.150
0.200
0.190
0.405
0.385
0.395
0.320
0.295
0.290
0.410
0.205
0.106
0.076
0.099
0.048
0.233
0.172
0.260
0.195
0.185
0.190
0.205
0.215
0.281
0.230
0.165
0.180
0.175
0.195
0.095
0.250
0.173
0.189
0.210
0.210
0.195
0.180
0.180
0.195
0.205
0.180
0.250
0.210
0.210
0.175
0.180
0.180
0.220
0.215
0.210
0.170
M =
molecular weight; Tb
=
50% normal boiling p oint,
F; d =
liquid density at 20 and
1
atm,
g/cm3; =
refractive in -
dex at 20
C
and
1
atm; v z l kinematic viscosity at 210
,
cSt.
O F
cSt. xpr x = inole fraction
of
paraffin, naphthene, and aromatic. References: no. 1-8: Lenoir and Hipkin
(1973);no. 9-42:
this
work
(eq 24).
Values in the parenthese s are kinematic viscosities at 100
private communication (1977).
Values
of n
for no. 9-42 a re calculated using the met hod suggested in
characterization factor for light hydrocarbons to be used
instead of V G C an d the n to develop a series of equa tions
similar to eq 10, 11, ,and 1 2 for prediction of the compo-
sition of light petroleum fractions.
Specific gravities
of
l ight paraff inic and naphthenic
hydrocarbons are plotted against the natura l logarithm of
their kinematic viscosities at 100 O F in Figure 2. An
almost linear relationship exists between S and In uloO for
paraffins and naph thene s, each with the same slope. Th e
following equations represent the lines
for paraffins: S = 0.0332 In
vloO
+ 0.7336 (13)
for naphthenes: S = 0.0332 In vloo + 0.7853 (14)
The se equations can reproduce data w ithin an average
deviation of less than 2 . Th e new characterization factor
for light hydrocarbons may be defined as a function of
S
and In u lW.
V G F = a + bS +
c
In u lW (15)
where V G F
=
viscosity gravity fun ction, new characteri-
zation parameter,
S ==
specific gravity a t 60160 O F , vloO
=
kinematic viscosity at 100
OF
St, and
a,
b ,
c
=
numerical
consta nts. Arbi trary values of 0.74 and 0.92 have been
chosen for the average V G F of paraffins and na phthen es,
respectively. Th us by substituti ng eq 13 and 14 into eq
15 the constants a b, and
c
can be determined and eq
15
becomes
V G F
= - 1.816 + 3.4848 0.1156 In vloo
(16)
Eq uat ion 16 gives the value of
V G F
for any hydrocarbon
or
fraction for which its specific gravity and kinematic
viscosity at 100 O F are known.
By following the same procedure a correlation relating
V G F to specific gravity an d kinem atic viscosity a t 210 O F
can be derived
V G F
= 1.948 + 3.5358 0.1613 In vzl0 (17)
in which
vzlo
is kinematic viscosity at 210 O F n centistokes.
Equations 16 and 17 which are similar to eq 3 a nd 4 give
almost the same value for V G F of a hydrocarbon
or
pe-
troleum fraction.
Using eq 16 an d 17, average value s of V G F for light
paraff ins, naphthe nes, and aromatics are 0.74, 0.92, and
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1980
l n ( k i n e m a t i c
V I S C O I I ~ ~ )
1
100' F
Figure 2. Viscosity-gravity relationship.
Table 111. Data on the Composit ion of Viscous Petroleum Fractions
composition
no. M Tb d n S
VI,
XD Xn
Xa
1
233 569.6
0.9082 1.50 16 0.9119
48.2 0.34 1 0.459 0.190
2 248
620.0 0.9360
1.5212 0.9397 66.7 0.304 0.430 0.2 26
3 267 652.4
0.9568 1.5366 0.9605
111.1
0.309 0.370 0.321
4
281
688.4 0.9 671 1.5452 0.9708 203.1 0.318 0.340 0.342
5 305 724.4
0.9742 1.5492 0.9779 516.5 0.329 0.322 0.349
6 245 582.2 0.8497
1.4719 0.8535
43.2 0.584 0.318 0.097
7 28 2
648.8
0.8709
1.4842 0.8746
58.7 0.565
0.307 0.128
8 325 717.2 0.8845
1.4919 0.8883 108.8 0.584 0.289 0.128
9 403 798.2
0.9001 1.5002
0.9046
336.0 0.590 0.280
0.130
10 265 614.6 0.8319 1.4637 0.8357
45.5
0.700
0.227 0.073
11 297 675.8
0.8425
1.4694 0.8463 59.4 0.694 0.224 0.081
12 523 937.0 0.8750 1.4865 0.8760
463.0 0.784 0.133 0.083
13 250
- - - -
0.8912 1.4896 0.8939 60.6 0.105 0.639 0.256
14 394
- - - - 0.8664
1.477 0.87 155.4
0.720 0.250
0.030
15
253
- - - -
0.877
1.4838
0.88
54.6 0.580
0.340 0.080
16 364
- - - - 0.907
1.5142 0.936 680.5 0.102 0.455 0.443
a =
molecular weight; Tb
=
normal boiling point,
O F
d
=
liquid density at 20
C
and
1
atm, g/cm3;
n =
refractive index
at 20 and
1
atm; S
=
specific gravity at 6 0/ 60 F; V,,
=
Saybo lt Universal Viscosity at
100 F,
SSU. References: no.
1-11:
Van Nesand Van Westen (19 51); no. 12: Witco (1973) ;no
1 3 :
Pennzo il(l9 75); no. 14-16:
A.S.M.E.
(1953).
Table IV. Results
of
Prediction
of
the Composition of Light P etroleum Fractions
abs dev, mole fraction
X P Xn
no.
of
m o lwt VG F
Xn
data source oils range Rirang e range xpra nge range av bias max av bias max
Lenoirand
8
100-230 1.041- 0.787- 0.19- 0.30- 0.039 -0.0 23 -0.125 0.043 -0.0 03 0.093
Hipkin 1.051 1.06 0.62 0.65
industrial 34 126- 171 1.044- 0.827- 0.26- 0.13- 0.0 33
-0.010
-0.09 5 0.04 0.019 0.114
company 1.055 0.950 0.66 0.53
1.055 0.95 0.66 0.65
total 42 100-230 1.041- 0.787- 0.19- 0.13- 0.034 -0.012 -0.125 0.041 0.015 0.114
Absolute deviation = Xpred - x e x p ~ ;ax = maximu m dev iation; av = ( l / N ) z : deviationl; bias = ( l /N)xdeviation;
N =
number
of
data points.
1.12. Average values for Ri of paraffins, naphthenes, and
aromatics are 1.046, 1.04, an d 1.066, respectively. There-
fore, Ri
and V G F
for a petroleum fraction can be estimated
by
Ri
=
1 . 0 4 6 ~ ~1 . 0 4 ~ ~1 . 0 6 6 ~ ~ (18)
V G F =
0 . 7 4 ~ ~0 . 9 2 ~ ~
1 . 1 2 ~ ~
( l 9 )
Physical properties of 45 light defined hydrocarbon mix-
tures were estimated using the composition of the m ixture,
properties of components from API Reseach Project 44
(1978), an d Kay's mixing rule. After regression of eq 18
and 19 with th e composit ions of th e 45 defined hydro-
carbon mixtures and solution simultaneously with eq
1,
the following expressions were derived for xP, , , a nd
x , .
-
8/16/2019 Riazi Daubert 1980
5/6
Ind.
Eng.
Chem. Process
Des. Dev.,
Vol. 19, No.
2, 1980
293
xP
= 23.94 + 24.21Ri 1.092VGF
X, = 41.14 39.43Ri + 0.627VGF
X, = 16.2 + 15.22Ri + 0.465VGF
(20)
(21)
(22)
Th e above equations can be used to predict the compo-
sition of an olefin-free petroleum fraction
if
Ri and VGF
are known. Equa tions 20, 21, and 22 are similar to eq 10,
11,
an d 12 for composition prediction of viscous fractions.
Since refractive indices of petroleu m fractio ns are no t
always known, it is imp orta nt to predic t refractive index
with a good degree of accuracy in order to estimate the
refractivity inte rcep t from eq 2. Hu ang (1977) correlated
molecular weight to boiling point, refractive index and
density as follows
(23)
=
7.7776 X
10-67-
2.11971-2.089d
b
where M = molecular weight, T b
=
norm al boiling po int,
OR
d =
density at 20
C
an d
1
atm, g /cm3, and I
=
characterization factor defined in eq
5 .
By rearranging eq
23 and 5, the following correlations for prediction of re-
fractive index of petroleum fractions were derived.
M S
200: I
=
3.583 x
10-3Tb1.0147(M/d)-0.4787
24a)
1
= (-)
+ 21
1 - I
where
n
= refractive index at 20 C , Tb = 50% boiling
poin t a t 1a tm , O R h4 = molecular weight, and
d
= liquid
density at 20
C
an d
1
atm , g/cm3. Equatio n 24 can
predict refractive index of light ( M
<
200) fractions within
an average deviation of about 0.5% while for heavy frac-
tions the error is abfout4-5%.
For
heavy fracti ons, a correlation similar to eq 24 can
be derived by use of data available on refractive indices
of heavy hydrocarbons in API Research Project 42 (1962).
After regression of dat a, the following equatio n was derived
M 200:
I = 1.4
X
10-3Tb1.0u M /d)-0 .3984
r i = (-)+
21
1 - I
The equations can predict refractive indices of heavy pe-
troleum fraction s within an average deviation of 0.2%.
Evaluation of the I?roposed Correlations
Tables I1 an d I11 show experime ntal dat a on the com-
position of light and heavy petroleum fractions from
various sources. All physical properties necessary to use
the proposed correlations are also given.
Equa tions 20, 21, and 22 were used t o predict th e com-
position of the light M < 200) fractions listed in Tab le
11.
A summary of results is given in Table IV, and
point-by -point evaluations a re available. Average devia-
tion s of 0.03 an d 0.04 mole fractions were obt ain ed for
x p
an d
x,,
respectively. Similar results for heavy fractions
are shown in Ta ble V using eq
10,11,
and 12 for prediction
of the composition of the fractions listed in Table 111.
Average deviations of
0.018
and
0.01
mole fractions for xp
an d x,, respectively, were obtained. Th e results are gen-
erally better tha n those of existing methods such as the
n-d-M
method.
Table VI shows a comparison
of
the use of experimental
vs
predicted compositions as inp ut to enthalpy and vis-
cosity prediction meth ods. As shown, predict ed compo-
-
8/16/2019 Riazi Daubert 1980
6/6
294 Ind. Eng. Chem. Process Des. Dev. 1980, 19 294-300
Table VI.
Predicted Compositions for Entha lpy and
Viscosity Predictions
Comparison
of
the Use of Experimental
vs.
av deva
no.
of
frac- exptl
pro pert y tions comp n pred comp n
liquid enthalpy 435 2.4 Btuilb 2.7 Btu/lb
vapor enthalpy 292 3.7 Btul lb
3.5 Btullb
viscosity at
38
2.9% 2.8%
100 F light)
2
10
F (light)
100 F (heavy)
210 F
heavy)
viscosity at 38 5.7% 5.2%
viscosity at
10
8.1% 8.5%
viscosity at 10 3.5%
3.5%
Absolute deviation
=
predicted property - experimen-
tal property.
perimental property)/experimental propert y]
x
100 av =
l/N)
deviation 1
sitions do not materially affect the results.
L i t e r a t u r e C i t e d
American Petroleum Institute (API) Research Project 42, Properties of Hy-
drocarbons
of
High Molecular Weight , American Petroleum Institute
(1962).
Deviation, %
=
[(predicted property ex-
iv = number of data points.
API Research Project 44, Selected Values
of
Properties
of
Hydrocarbons and
h a t e a Compounds' , Taoles of Physical and Thermodynamic Properties of
Hydrocarbons.
A
and M Press, College Station, Texas (extant 1978).
A S M.E. Research Cornminee on Lubrication, 'Viscosity and Density of Over
40 Luoricating Fluids of Known Composition at Pressures
to
150,000 psia
and Temperatures to 425 OF ', Report No. 1. 1953.
Boelhower. C.. Waterman, H. 1.. J . I n s t Pel., 40. 116 (1954).
Hili. J B.. Coats, H. B.. I nd Eng. Chem.. 20, 641 (1928).
huang. P. K.. Ph.D Thesis, Department of Chemical Engineering, The Penn-
hdang. P. K.. Daubert, T. E.,
I n d
Eng. Chern. Process De s Dev
13,
359
Kurtz. S. S I r.. King. R. W., Stout. W. J.. Peterkin, M.
E., Ana l
Chern 30,
Kurtz. S. S Jr., Ward, A. L.. J . Franklin I n s t 222. 563 (1936).
K d z , S. S., Jr.. Ward. A.
L .
J . Franklin Inst 224, 583. 697 (1937).
Lenoir. . M.. Hipkin. H. G., J . Chern Eng.
Data
18, 195 (1973).
Private communications, Witco Chem. Co.,
1973.
Private communications. Pennzoil Co., 1975.
Private communications, Indbstrial Co., 1977.
Riazi, M. R.. Ph.D. Thesis. Department of Chemical Engineering, The Penn-
sylvania State University, University Park, Pa.. 1979.
Van Nes, K Van Westen, H. A. . Aspects of the Constbtion of Mineral Oils .
Elsever PJOiiShing Co.. InC.. New Yorrc, 1951.
Waterman. H I , Boehower. C Cornelissen,J..
Correht;on Between physical
Constants and Chemical StrLcture , Elsevier Publishing Co.. Inc.. New York,
1958.
sylvanla State University, University Park, Pa., 1977.
(1974).
1225 (1958).
Received f o r rer ieu Ju l y
23,
19'79
. k e e p r e d
December
7 , 1979
The Department of Refining of the American Petroleum Institute
provided major financial
s u p p o r t
of this research.
Kinetics of Oxydesulfurization of Upper Freeport Coal
D. Slagle, Y. T. Sh ah, and J.
B.
Josh1
Department of Chem ical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 5261
T he
kinetics of the oxidation of pyritic
sul fur
organic sulfur, and carbon for the
Upper
Freeport coal are investigated.
Experiments were conducted in a semi-batch
manner.
The effects of batch time (0-2400 s), emperature (150-210
C),
artial pressure of oxygen (0.69-3.44 MPa), and total pressure
(3.44-6.88
MPa) were studied. Two alternate
mechanisms have
been
proposed for t h e oxidation of pyritic s u l f u r . In one mechanism the
fine
pyrite particles
are assumed to b e uniformly
distributed in
coal particles and the continuous reaction model was found to hoM where
the rat e of reac tion is second order with respect to pyritic sulfur. In the other mechanism, the pyrite particles
are assumed to exist free from coal and
the
shrinking core model was found to hold
where the
rate of reaction
is controlled by diffusion through ash. Both the carbon oxidation and organic sulfur reactions are z ero order with
respect to carbon and organic
sulfur,
respectively.
The
activation energies for all three reactions agree closely
with those reported in the literature.
I n t r o d u c t i o n
T he sulfur in coal occurs in three form s: pyritic, organic,
or sulfate. Pyrite s, classified as compound s with the for-
mula FeS, (where the sta ndard value of
x
is
2),
accounts
for the bulk of the sulfur in Eastern coals. Organic sulfur
is a broad classification containing any sulfur which is
chemically bound to th e actual coal matrix. Organic sulfur
is th e domina nt sulfur form in Western coals. Sulfates
con stitu te less than a few percent of the tot al sulfur in most
coals.
The direct burning of coal causes the production of
noxious sulfur oxides
(S0,'s).
Pres ently , control of sulfur
oxide emissions is achieved mainly by either stack gas
scrubbing or physical coal cleaning techniques. Th e former
process is both expensive and energy intensive. Th e latter,
although relatively inexpensive and simple to o perate, is
less effective. In fact, depending on the sulfur composition
of the feed coal, a plant b urning physically pre-cleane d coal
0196-4305/80/1119-0294$01.00/0
may also have to employ flue gas scrubbing in order to
meet environmental sta ndard s (T rindad e et al., 1974).
A
possible alternative to these processes is chemical coal
cleaning, i.e., remov al of th e sulfur by me ans of a chem ical
reaction before burning t he coal.
There are presently six major chemical coal cleaning
methods being developed (Oder et al., 1977). O ne of th e
promising processes is the oxydesulfurization process
(Friedman and Warzinski, 1977; Friedman et al., 1977).
In thi s process, the s ulfur is removed by oxidizing coal in
the presence of water. Th e process is operated at pressures
between 1.6 and 10 M Pa and temperatures between
150
and 220
C.
Normally air is used as the gas phase.
The purpose of this paper is to report a kinetic study
for the D.O.E. oxydesulfurization process. Kinetic rate
expressions for the inorganic and organic sulfur removal
reactions and carbon oxidation reaction for Upper Freeport
coal are presented.
980 American Chemical Society