Naworski, J. S., Jr., Ph.D. thesis, Cornel1 University, 1966. Phillips, R. M., M.S. thesis, Purdue University, 1965. Schmerling, L., in “Chemistry of Petroleum Hydrocarbons,” Vol. 111, p. 363, B. T. Brooks et al., eds., Reinhold, New York, 4
Shlegeris, R. J., Ph.D. thesis, Purdue University, 1967. Zimmerman, C. A., Kelly, J. T., Dean, J. C., IND.END. CHEM. PROD.RES.DEVELOP. 1, 124 (1962).
n cc
1723.
Schmerling, L., Znd. Eng. Chem. 45, 1447 (1953). Schmerlinc. L.. J . Am. Chem. Sac. 67. 1778 (1945’3. Schmerling; L.; in “Friedel-Crafts and Related’Reactions. Vol. 11. Alkylation and Related Reactions,” G. A. Olah, ed., Interscience, New York, 1964.
RECEIVED for review March 21, 1968 ACCEPTED August 29, 1968 Division of Petroleum Chemistry, 156th Meeting, ACS, Atlantic City, N. J., September 1968.
HYDROCRACKING OF GAS OIL S. A. Q A D E R
A N D G.
R. H I L L
De$artment of Fuels Engineering, University of Utah, Salt Lake City, Utah 84112
Gas oil boiling in the range 300” to 430’ C. was hydrocracked in a conventional continuous fixed-bed tubular flow reactor over a dual-functional catalyst. Gasoline of almost the same composition was produced in yields of 60, 82, and 58% in the single-pass, double-pass, and recycle operations, respectively, with diesel oil of 50 diesel index as a by-product. Hydrocracking of gas oil proceeds through a mechanism involving a combination of simultaneous and consecutive bond-breaking reactions followed by isomerization and hydrogenation of the products. The over-all kinetics observed indicated that gas oil hydrocracking, desulfurization, and denitrogenation reactions are all first-order and the rate constants can be represented hr.-’, k, = 0.681 4 X 1 O5 e-16’a00/RT hr.-I, and k, = 0.8253 X 1 O5 e-17,400’RT by: k, = 1 X 10’ e--21J00/RT hr.-I The cracking reactions involving the breakage of C-C, C-S, and C-N bonds on the acidic sites of the catalyst are rate-determining.
is being developed and practiced in the petroleum industry for converting different types of charge stocks to middle distillates, gasoline, or liquefied petroleum gases. The incentives of getting a variety of valuable Products from inferior grade feed stocks led to the development of a number of large-scale processes (Craig and Forster, 1966; Duir, 1967; Prescott, 1966) in the recent past. However, detailed experimentation was not done to explore the mechanisms and product distributions involved in the hydrocracking of various petroleum fractions, although some work was reported on the reaction mechanisms of some pure hydrocarbons. Flinn et al. (1960) and Archibald et al. (1960) studied the product distribution and reaction mechanisms in the hydrocracking of some pure hydrocarbons over dual-functional catalysts. Products rich in isoparaffins were formed because of a mechanism combining rapid isomerization with cracking and subsequent hydrogenation of the olefinic fragments. Sullivan et ai. (1964) found considerable cyclization of the side chains \\-hen some aromatic hydrocarbons were hydrocracked over a nickel sulfide catalyst. The products were found to be predominantly Tetralins and indanes of lower molecular lzeight than that of the reactant. lVyers et al. (1962) and Larson et al. (1962) investigated the performance of several catalysts for hydrocracking gas oil and furnace oil fractions and reported that the acid sites crack and isomerize olefin intermediates and the products get saturated at the hydrogenation sites. Kozlowski et al. (1962) hydrocracked gas oils boiling in the range 300’ to 450” C. and obtained kerosine-type jet fuel with freezing points below -15.5’ C. in yields of about 20 to 40%. I n the present communication, the results of the hydrocracking of a gas oil in a continuous fixed-bed bench scale YDROCRACKING
98
I&EC PROCESS DESIGN A N D DEVELOPMENT
reactor over a dual-functional catalyst carried out as a part of the program on the processing of mixtures of coal-derived liquids and petroleum fractions are reported. The influence of process conditions on product distribution is discussed and a kinetic evaluation of the data is presented. Experimental
Materials. A gas oil fraction (Table I) was used as the feed. The catalyst (commercial) contained 6% nickel and 19% tungsten, both as sulfides, supported on silica-alumina in the form of pellets of 0.083-inch diameter and 0.125-inch height, with a surface area of 212 sq. meters per gram. 5-A molecular sieves were of chromatographic grade. Active carbon was used as adsorbent. Equipment. T h e hydrotreating unit (Figure 1) consisted of a vertical tubular stainless steel reactor of 0.75-inch inside diameter and 40-inch length with extensive means for controlling temperature, pressure, and gas and liquid flow rates. T h e reactor was heated uniformly by a tubular ceramic furnace of 1.5-inch inside diameter and 38-inch length, which was well insulated. The first 20-inch length of the reactor from the top was packed with ceramic beads of 0.17-inch diameter, the next 6.5 inches with the catalyst (60 cc.), and the following 12 inches again with ceramic beads. The top bed of ceramic beads acts as the preheating zone. The temperature a t the center of the catalyst bed was measured with a thermocouple placed between the reactor and furnace walls. Temperature measurements at several points along the reactor tube indicated that the difference in temperature inside the reactor and the space between the reactor and furnace walls a t each point was less than 1” C. when the temperature was controlled for one hour or longer. The temperature of the catalyst bed was maintained constant throughout. The hydrogen supply was taken from a hydrogen cylinder with a maximum pressure of 2300 p.s.i. Procedure for Hydrocracking Experiments. T h e equip ment was first flushed with hydrogen to remove air, pressurized,
Table 1.
Analysis of Gas Oil
Gravity, "API Sulfur, wt. 70 Nitrogen, wt. % ' Distillation, ' C. IBP 50% 90% FBP Hydrocarbon types, vol. Saturates Olefins Aromatics
31.80 0,9436 0,8046 300 342 406 430 70
65 7 28
and heated to the desired temperature. T h e pressure was then adjusted to the experimental value and the oil was fed a t the desired rate. T h e initial 2 hours were taken as a n offstream time for bringing the reactor and product recovery system to a steady state. T h e hydrogen to oil feed ratio was maintained a t about 500. T h e values of space velocities (volume of liquid feed per hour per volume of catalyst) varied in the range of =klOyoand were rounded off. The liquid product was collected in the separator and the gases were passed thrpugh an active carbon tower to adsorb any uncondensed product and a gas meter to measure the rate and total volume passed. Four gas samples were withdrawn during each experiment for analysis. The difference in the weight of active carbon before and after the experiment was taken as the amount of uncondensed naphtha, which varied between 1 and 2y0 of the feed. T h e yield of total product was taken as loo%, and 100 minus the liquid product was taken as gas. T h e yield of the liquid product varied between 93 and 1 0 0 ~ owith , an initial boiling point between 46' and 59' C. The conversion was taken as the total product minus the product, including gas, boiling u p to the initial boiling point of the feed. T h e single-pass product, boiling above 200' C., was hydrocracked under the same conditions to get the double-pass product. I n the recycle operation, the product from the single pass, boiling above 200' C., was mixed with the feed in
the ratio of 33 to 100 cc. of feed. The product refers to singlepass product unless otherwise mentioned. The liquid product was distilled (ASTM, E 133-58) into light naphtha, boiling u p to 100' C., heavy naphtha, from 100' to 200' C., gasoline, boiling u p to 200' C., middle distillate, from 200' to 300' C., and diesel oil, from 200' C. and above. The kinetic data were obtained at a constant pressure of 1500 p s i . Product Analysis. Sulfur was determined by the bomb method and nitrogen by the C-H-N chromatographic analyzer, F. M. Model 185. Hydrocarbon-type analysis of naphtha, gasoline, and middle distillate was done by the fluorescent-indicator-adsorption method (ASTM, D 1319-65T). T h e hydrocarbon types in the feed were determined by washing with 20% sulfuric acid for olefins and with a mixture of 7070 concentrated sulfuric acid and 30% phosphorus pentoxide for aromatics and saturates (ASTM, D 1019-62). The naphthenes in naphtha and gasoline were estimated by the refractivity intercept method (ASTM, D 1840-64). T h e normal paraffin content was determined by adsorption on 5-A molecular sieves in a glass column of 0.5-inch diameter and 1.5-foot height. T h e isoparaffins were obtained by the difference. The diesel index was calculated from API gravity and aniline point. The gas analysis was done by gas chromatography in the F. M. Model 720 dual-column programmed temperature gas chromatograph. Results and Discussion
Product Distribution. T h e conversion to gasoline, middle distillate, and gas increased with a n increase in temperature and decrease in'space velocity. T h e highest gas oil conversion of 96% was obtained a t 500' C., 0.5 space velocity, and 1500p.s.i. pressure (Figure 2). Gasoline of almost the same composition was produced in yields of 60, 82, and 58% in the singlepass, double-pass, and recycle operations, respectively. Diesel oil with a diesel index of about 50 was produced as a by-product in yields of about 33 to 35y0,while the dry gas varied between 6 and 8% (Table 11). The light naphtha, heavy naphtha, gasoline, and middle distillate increased with total conversion,
H
Figure 1.
Flow sheet of hydrotreating unit
1. 2A, 26, 2C. 3. 4. 5. 6. 7. 8. 9. 10. 11.
High pressure pump Pressure gages Reactor Themocouple Ceramic furnace Insulation Temperature controller Condenser Separator Active carbon tower Gas meter VOL. 8
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99
Table II. Yields and Nature of Gasoline and Diesel Oil (Temperature, 500' C. Sp. vel., 0.5) SingleDoubleYield and Properties Pass Pass Recycle Gasoline Yield, vol. yo 60.0 82.0 58.0 Hydrocarbon types, vol. yo n-Paraffins 20.5 22.0 21 .o Isoparaffins 38.0 36.0 39.0 Aromatics 14.0 15.0 15.0 Naphthenes 25.5 24.0 23.0 Olefins 2.0 3.0 2.0 Diesel oil Yield. vol. % 33.0 10.0 35.5 Diesel index 49.0 38.0 50.0 8.0 7.0 6.5 Gas, vol. I "
G asoiine
1
Heavy naphtha
2 3 4
Middle D i s t i l l a t e Light naphtha
2ol
1
/: /
lo
$
i
9
30
Sp Vel. 1.5
r/)
4 (3
u
W
IT
'1
3'0
2'0
50
40
70
60
a
-l
a
J
1 L-
E
n
w
L a
J n 10 0
. . . . .
50
30
1
70
1
90
TOTAL CO NV E R S I 0 N, VOL."/o
60
5OO0c
0
A
425'C 400°C
w
Figure 3. Product distribution at levels of conversion 2.4
I
different
S p Vel -4
0.5 1.0
1,6Ez2
z
J
z
1.5
6
a
2.0
1.2
2.5
I
0.5
1.0
I
1
2.0 2.5 SPACE -VELOCITY 1.5
J
3.0
Figure 2. Effect of temperature and space velocity on product distribution Pressure 1500 p.r.i.
but the yield of middle distillate decreased with an increase in gasoline a t lower space velocities (Figure 3). The ratio of gasoline to middle distillate increased almost linearly with temperature at a space velocity of 3.0 but at each lower space velocity there was a sudden rise in the curve a t a specific temperature (Figure 4). Gas oil molecules appear to be cracking primarily to form middle distillate, gasoline, and gas. When the severity of cracking increases a t higher temperatures and lower space velocities, middle distillate formed starts cracking simultaneously to gasoline and gas. As the cracking severity further increases, the gasoline also starts cracking simultane100
I&EC PROCESS D E S I G N A N D DEVELOPMENT
0 400
450
500
TEM PE RATUR E , O c
Figure 4. Effect of temperature and space velocity on gasoline-middle distillate ratio Pressure 1500 p.s.i.
ously to light naphtha and gas, as can be seen by the reduction in the gasoline to middle distillate ratio above 475' C. and a t 0.5 spacevelocity (Figure 4). The heavy and light naphtha increased with gasoline yield but their ratios decreased (Figure 5). The olefinic and naphthenic contents remained almost the same with an increase in isoparaffins and aromatics, while normal paraffins decreased (Figure 6). At higher yields, gasoline contains more light
4.0
Light. naphtha Heavy naphtha
1.6
201
3.0
1000
2000 2 2 0 0
1500
P R E S S U R E , psi
$
"0
Figure 7.
2.c
>
Effect of pressure on product distribution Space velocity 1.0
-U0
4
1.0
0.
100
I
)
30
I
40
I
-
5OO0C
I
50
60
GASOLINE, V O L . %
4 5 O'C
60 -
Figure 5. Product distribution a t different levels of gasoline formation 4 OO'C
I L
60
-
-
,
40 1000 O1 Olefins
2 Aromatics 3 Yield 4 . Nophthenes 5 . lsoporoffins 6 N -paroffins
Q
I b-
2a
30
Z
O 1 30
40
4b 60 GASOLINE, VOL ,'lo
Figure 6. Composition of naphtha a t different levels of gasoline formation
.
4OO0c I
1500 2000 2 2 0 0 PRESSURE, psi
Figure 8. Effect of pressure on desulfurization and denitrogenation Space velocity 1.0
naphtha relative to heavy naphtha with more isoparaffins and aromatics. Isomerization increases with cracking and immediately follows the latter. Hydrogenation of the olefinic products takes place under all conditions of hydrocracking, as shown by the low olefinic content of naphtha. Partial hydrogenation of polycyclic aromatic hydrocarbons to the corresponding hydroaromatics also takes place with subsequent cracking of the latter to mono-ring aromatics boiling in the gasoline range. Aromatization reactions may be occurring to some extent. Dehydrogenation of the naphthenes does not seem to be taking place to any appreciable extent under the experimental conditions employed (Figure 6). VOL. 8
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JANUARY
1969
101
1 =
2
The effects of temperature and space velocity on total conversion, desulfurization, and denitrogenation are shown in Figure 9. The plots of the reciprocal of LHSV us. log X J X , (Figures 10 to 12) were almost linear and the first-order rate constants are represented by Equations 2 to 4.
400'C
= 425'C
3 = 450'C 4 = 475OC
- d (gas oil)
=
k , (gas oil)
=
k , (sulfur)
dt
- d (sulfur) dt
0
I
- d (nitrogen) = k , (nitrogen) dt
I
100
(3)
(4)
where k,, k,, and k , are rate constants for gas oil hydrocracking, desulfurization, and denitrogenation, respectively. There was no change in the concentration of hydrogen in the system, since the experiments were conducted at a constant pressure of 1500 p.s.i. Hydrogen atoms might have been involved in the reaction, but their concentration does not show up in the rate equation and constitute one of the constant factors. Figure 13 is the plot of the rate constants, k,, k,, and k,, us. the reciprocal of the absolute temperature. Linear plots, showing Arrhenius temperature dependence, were obtained and the rate constants can be represented by Equations 5 to 7 .
80
60 40 20
k , = 1 X 107 ,-Zl,lOO/RT hr.-1
(5)
k, = 0.6814 X IO5 e - 1 6 , * 0 0 / R T hr.-l
(6)
k , = 0.8253 X l o 5 e-17,400/RT hr?
(7)
The following values of enthalpies and entropies of activation were calculated from plots of log k / T us. 1 / T by applying the Eyring equation (Figure 14).
0.5
1.0
1.5
2.0
S PAC E
2.5
3.0
-V ELOC I T Y
Figure 9. Effect of temperature and space velocity on conversion Pressure 1500 p.s.i.
The total conversion increased u p to 1500 p.s.i. but remained almost constant at higher pressures. The gas yield and isonormal ratio increased with conversion (Figure 5) but were not affected by pressure (Figure 7). Desulfurization and denitrogenation increased with pressure (Figure 8). Kinetics. T h e over-all rates of gas oil hydrocracking, desulfurization, and denitrogenation can be expressed by a simple first-order kinetic Equation 1. Xi
In-
x,
= k
1 LHSV
AH,#
= 19,100 cal./mole
ASf
= -44.18 e.u.
AH,'
= 16,500 cal./mole
AS,#
= -44.35 e.u.
AH,#
= 16,000 cal./mole
AS,# = -42.40 e.u.
The high negative values of AS# are indicative of the formation of an immobile activated complex which lost several degrees of freedom followed by dissociation. The product distribution data obtained in the present investigation indicated that the hydrocracking of gas oil produces middle distillate, gasoline, and gas through a mechanism involving a combination of simultaneous and consecutive cracking reactions followed by isomerization and hydrogenation of the products. The over-all surface reactions occurring during the catalytic hydrocracking of gas oil can thus be represented by steps i to vii,
C,Hz,+z
+
CbHzb+z f CCHZC
(9
(1)
where xt
x,
= initial concentration, weight % ' = final concentration, weight %
LHSV = liquid hourly space velocity, volume of liquid feed per hour per volume of catalyst k = reaction rate constant 102
I&EC PROCESS D E S I G N A N D DEVELOPMENT
AN
+ Hz
AR'
+ HB
+
-+
+ R"H AH + R'H
AR'
( 4 (vii)
0.6
I
/
Figure 10. First-order plot for gas oil hydrocracking Pressure 1500 p.s.i.
1 / SPACE - V E L C C I T Y
I-
1.8
-
1.6
-
1.4
-
1.2
-
475-c
4 50’C
4 2 5OC
0
Figure 1 1. First-order plot for desulfurization Pressure 1500 p.s.i.
0.8
0.61 400OC
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-
1/ SPACE V E L 0 C I T Y
where A R and AN represent alkyl aromatic and hydroaromatic compounds, respectively. A represents fused aromatic rings, K represents fused naphthenic rings, and R, R’, and R ” represent alkyl chains. Step i represents the cracking of parafins giving rise to lower molecular \\eight paraffins and olefins, the extent of degradation depending upon the reaction conditions and the nature of parent molecules. Steps iii and iv represent hydrogenation reactions and step ii represents isomerization of the product olefins. T h e hydrocracking of olefins and naphthenes proceeds in a similar manner. Steps v and vii represent dealkylation of alkyl aromatic hydrocar-
bons, while step vi represents hydrocracking of hydroaromatics. T h e cracking reactions shown above involve the breakage of C-C bonds present in different types of hydrocarbons and the splitting mainly proceeds through the carbonium ion mechanism proposed by Greensfelder et d.(1949). Desulfurization and denitrogenation reactions involve the rupture of C-S and C--N bonds with subsequent interaction of hydrogen with the fragmented molecules, forming hydrogen sulfide and ammonia, respectively. Sulfur and nitrogen removal may proceed through an accelerated radical mechanism, as can be represented by steps viii to xiii, VOL. 8
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JANUARY
1969
103
1.4
1.2 1.0
4;
Figure 12. First-order plot for denitrogenation
-In 0
OA
475OC
0.6 450'C
Pressure 1500 p.s.i.
0.4
425'C
0.2
40 0°C
0 0
0.2
0.4
0.6
1.0
0.8
1.2
1.4
1.6
1.8
2.0
1 / SPACE-VELOCITY
-2'ol
0.0 -
- 0.2 - 0.4-
I\ Y
I
Gas Oil
- 0.6 -
-
0.1
- 4.01 1.2
-0.1
I
I
I
I
1.3
1.4
1.5
1.6
1 1 ~ x 1 0 ~
Figure 13. Arrhenius plot for gas oil hydrocracking, desulfurization, and denitrogenation
104
1.5
1.6
lo3
Figure 14. Eyring plot for gas oil hydrocracking, desulfurization, and denitrogenation
Su l f u r
- 0.3 -
1.2
1.4 1I T x
-
- 0.7 1
I
1.3
I&EC PROCESS D E S I G N A N D DEVELOPMENT
where R1, Rs, R3, and R4 represent hydrocarbon radicals. Steps viii and ix represent breakage of C-S and C-N bonds in all types of sulfur and nitrogen compounds present in the gas oil, respectively. Steps x to xiii represent the reactions between hydrogen and the fragmented heterocyclic molecules to form products. The steps listed above are the principal surface reactions that can possibly occur and indicate that the over-all kinetics observed resulted from a sequence of this type. The results of kinetic studies in heterogeneous catalytic systems may involve serious complications due to the interplay between the reactions occurring on the active sites of the catalyst and the adsorption of reactants on the catalyst surface. The nonspecificity of most of the catalyst sites leads to different types of reactions Xvith different paths occurring on the same active site. This may make the sequence of reactions observed in the apparent kinetics differ from the true sequence of the surface reactions. Large modifications may also be produced in the apparent kinetics by heat and mass transfer and
residence time distribution in catalyst beds along with the possibility of the occurrence of liquid and vapor phase channeling when the reactions are carried out in continuous fixed-bed systems over solid catalysts. However, the sequence modifications may not occur if the surface reactions control the reaction rate completely. Though this condition may often prevail in heterogeneous catalytic systems, there can be several systems where this does not hold good, as discussed by Smith and Prater (1967). The magnitude of energies and enthalpies of activation obtained in the present investigation suggests that chemical reactions but not physical processes are rate-controlling. The product distribution data indicated that hydrogenation was complete under all experimental conditions, as can be seen by the negligible amounts of olefins in the products. In the presence of an initial excess of hydrogen, the reactions between hydrogen and the fragmented heterocyclic molecules occur freely and rapidly. Thus, any step involving hydrogenation reactions may not control the reaction rate. The effect of hydrogen pressure on gas oil conversion (Figure 8) also suggests the occurrence of a reaction consisting of a primary step in which hydrogen is not involved and which is normally ratecontrolling and a faster subsequent step involving hydrogen Ivhich may limit the rate only when hydrogen concentration is low. Therefore, cracking and isomerization reactions must be rate-controlling, as was also suggested by TYeisz and Prater (1957) and Keulemans and Voge (1959). Products formed in catalytic hydrocracking contain an excess of branched isomers that can be predicted by thermodynamic equilibrium (Archibald et al., 1960; Flinn et al., 1960), which is possible
only if the isomerization of the products occurs very rapidly and the isomerized species leave the catalyst surface without re-adsorption before reaching equilibrium conditions. The excess isoparaffin content of gas and naphtha (Figure 5) indicates that isomerization is fast and cannot control the reaction rate. Therefore, the cracking reactions involving the rupture of C-C, C-S, and C-N bonds must be rate-limiting in the hydrocracking of gas oil over the dual-functional catalyst. literature Cited
Archibald, R. C., Greensfelder, B. S., Holzman, G., Rowf, D. H., Ind. Eng. Chem. 52,745 (1960). Craig, R. G., Forster, H. A., Oil Gas J . 45, 159 (1966). Duir, J. H., Hydrocarbon Process. Petrol. Refiner 46, 127 (1967). Flinn, R. A., Larson, 0. A., Beuther, H., Znd. Eng. Chem. 52, 153 i1960). GGeensfilder, B. S., Voge, H. H., Good, G. M., Ind. Eng. Chem. 41, 2573 (1949). Keulemans, A. I. M., Voge, H. H., J . Phys. Chem. 63,476 (1959). Kozlowski. R. H.. Mason, H. F.. Scott. J. W..’ IND.ENG.CHEM. PROCESSDESIGN DEVELOP. I , 2i6 (1962). Larson, 0. A., Maciver, D. S., Tobin, H. H., Flinn, R. A,, IND. ENG.CHEM.PROCESS DESIGN DEVELOP. 1, 300 (1962). Myers, C. G., Garwood, W. E., Rope, B. W., Wadlinger, R. L., Hawthorne, W. P., J . Chem. Eng. Data 7, 257 (1962). Prescott, J. H., Chem. Eng. 73, 142 (1966). Smith, R. L., Prater, C. D., Chem. Eng. Progr. Symp. Ser. 63, No. 73, 105 (1967). Sullivan, R. F., Egan, C. J., Langlois, G. E., J . Catalysis 3, 183 (1964). Weisz, P. B., Prater, C. D., Adam. Catalysis 9, 575 (1957). RECEIVED for review March 27, 1968 ACCEPTED July 1, 1968 Research work supported by Office of Coal Research and the University of Utah.
POLYMER REACTORS AND MOLECULAR WEIGHT DISTRIBUTION Role of Viscosit/v and Recycle in Reactor Qsterns A. W. T. H U I AND A. E. H A M I E L E C Chemical Engineering Department, .Mc.Master University, Hamilton, Ontario, Canada
A polymer reactor model (isothermal, backmixed) has been developed using free-radical kinetics which account for the effect of viscosity on rates of initiation and termination. This model was used to simulate the transient and steady-state behavior of a system of reactors which interact via recycle streams containing d e a d polymer. Reactor configurations included one to 12 reactors in series and parallel operation. A systematic study has shown that recycle of dead polymer may b e used to increase capacity and control molecular weight distribution.
investigation forms part of a continuing study of POreactors (Duerksen et al.. 1967: Duerksen and Hamielec. 1968a. b : Hamielec et al., 1967; Hui and Hamielec, 1968). This paper reports the results of a computer study of the transient and steady-state behavior of a system of isothermal, backmixed reactors which interact via recycle streams conHIS
Tlymerization kinetics and simulation of polymer
,
I
taining dead polymer.
Reactor configurations included:
Three reactors in series at steadv state with recvcle and no intermediate feed. Three reactors in series at steady state with recycle and intermediate feed. One to 12 reactors in series at steadv state with no recvcle and no intermediate feed. VOL. 8
NO. 1
JANUARY 1969
105
