= NIZ’ f ( Y ,Z’,
Hence,
5 [NAZ’ dt
JXY
f(c,
1
Y
f(c, X
c = concentration of carbon, lb carbon/lb catalyst c, = mean concentration of carbon in vessel i, lb carbon/lb catalyst f l = carbon distribution function for exit stream of regenerator f2 = carbon distribution function for exit stream of mixed reactor f3 = carbon distribution function for exit stream of plug flow riser iteration carbon distribution function coke-burning constant in regenerator, (sec) -’ coke-forming exponent in Equation l a time of catalyst exposure t o oil, see dimensionless parameter for the regenerator mean residence time in regenerator, minutes mean residence time in backmixed reactor, minutes os = residence time in plug riser, minutes
Z’, t ) d c =
Y
Q
t)R(Y)
Z’, t ) d c - QJ
f!c, 2’ X
+ AZ’,t ) d c +
NAZ’ f ( X , Z’, t ) R ( X )- NAZ’ f ( Y ,Z’, t ) R ( Y )
Since this is true for an arbitrary interval,
literature Cited
Behnken, D. W., Horowitz, J., Katz, S., Ind. Eng. Chem. Fundam. 2, 213 (1963). Voorhies, A,, Ind. Eng. Chem. 37, 319 (1945). Weisz, P. B., J . Catal. 6, 425 (1966). Nomenclature a = combined feed coking constant, lb carbon/
lb catalyst- (sec)” b = coking constant, lb carbon/lb catalyst
RECEIVED for review January 26, 1970 ACCEPTED June 1, 1970
Correction
KINETICS AND DYNAMICS OF CATALYTIC CRACKING SELECTIVITY I N FIXED-BED REACTORS
In this article by V. W. Weekman, J r . [IND.ENG.CHEM. PROCESS DES. DEVELOP.8, 385 (1969)], the following correction should be made: The second term within the large brackets in Equation 6 should read ~
yiKo --
K?
640
Ind. Eng. Chem. Process Des. Develop., Vol. 9, No. 4, 1970
e
K2 KOYI
