Page 194 - Elements of Chemical Reaction Engineering Ebook

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See. 4.4 Pressure Drop in Reactors "3
Example 4- 7 Pressure Drop with Reaction-Numerical Solutiort

Rework Example 4-6 for the case where volume change is nor rlegiccted in th.
Ergun equation and the two coupled differential equations
of conversion and preasure u itii ~dti!) \t sscight are solved
1 Solution
I
Rather than rederive everything starting horn the
etry, and pressure drop equations, we will use th
4-6 Combining Equationc (E4 6.1) and (E4-6.8) g I

Next. we let

E3- / .3)

(E1-7.4 j

For the reaction conditions descnbed in Example 4-6, we habe the bomindarJ condi-
tioris W = 0, X = 0, and y = 1.0 and the parameter values a = C: s"!~b/lb cat,
E = -0.15, k' = 0.0266 Ib mol/h.Ib cat, and FAo = 1.08 Ib mol/h.
'4 large number of ordinary differential equation solver software pacKages (i.e.,
ODE solvers) wfiich are extremely user friendly have become available. We shall
use POLYMATH to solve the examples in the pnnted text. However, the CD-ROM
4
contains an example that uses ASPEN, as v~ell as all the MATLAB and PlOLY-
MATH solution programs to the example prcprams. With POLYMATH one simply
Program examples enters Equations (E4-7.3) and (E4-7.4) and the corresponding parameter value into
POLYMATH, the computer (Table E4-7.1 1 with the l~llld~ (rather, boundary) conditions and they
MatLab can be are solved and displayed as shown in Figure E4-7.1,
loaded from the
CD-ROM (see We note that neglecting EX in the Ergun equation in Example 4-6
the Introduction) (EX= -0.09) to obtain an analyticai solution resulted in less than a 10% error.

Developed by Professor M. Cutlip of the University of Connecticut. and Professor M.
Shacham of Ben Gurion University. Available from the CACHE Corporation, P.O.
Box 7939, Austin, TX 78713.