Riazi Daubert 1980

8/16/2019 Riazi Daubert 1980

1/6

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

196-4305/80/1119-0289$01.00/0


2/6

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


3/6

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


4/6

292 Ind. Eng. Chem. Process Des. Dev., Vol. 19, No. 2,

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 , .


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-


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

Riazi Daubert 1980

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