Page 489 - Elements of Chemical Reaction Engineering Ebook

460 Steady-State Nonisothermal Reactor Design Chap. 8

From a mole balance on species i, we have

(8-58)

and from (8-44),

@ = Uu(T,- T)
dV
Differentiating Equation (8-19) with respect to volume, V:

-
dH. - - dT (8-59)
I
dV c ' -
P'dV
Neglecting the work term and substituting Equation (-8-58), (8-59) and (8-44)
into Equation (8-57), we obtain

Rearranging, we have

PFRIPBR (8-60)

This equation is coupled with the mole balances on each species [Equation
(8-58)]. Next we express rA as a function of either the concentrations for liquid
systems or molar flow rates for gas systems as described in Section 3.4.
1 These forms of the 1 For. a CSTR the energy balance can be written as
energy balance
will be applied to
multiple reactions
I ' Rearranging gives

CSTR (8-62)

Table 8-3 gives the algorithm for the design of PFRs and PBRs with heat
exchange for case A: conversion as the reaction variable and case B: molar
flow rates as the reaction variable. The procedure in case B must be used when
multiple reactions are present.
Having considered the exothermic liquid-phase reaction with constant
heat capacities, we now consider an endoQennic gas-phase reaction with vari-
able heat capacities.