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See. 6.3   Algorithm for Solution to Complex Reactions         307
                                   -                 TABLE E6-6.1.  POLYMATH PROGRAM          -

                                   -    Equations                                       Initial Values
                                    d(ch) /d(t) -rl+r2                                    0.021
                                    d(cm) /d(t)=rl                                        0. 01135
                                    d (cx) /d (t) =-rl+rZ                                 0
                                    kl=55.2
                                    k2=30.2
                                    rlr-kl*cm* (ch**.5)
                                    rZ=-k2*cx* (ch**.5)
                                    tD =  0,   tf =  0.5
                                   -                                                          -

                                                     A
                                                           I











                                                          0.0  0.1  0.2  0.3  0.4  0.5
                                                                    (hr)
                                I
                                                 Figure E6-6.1  Concentration profiles in a PFR.

                                     16.3.7  Multiple Reactions in a CSTR

                                     For a CSTR, a coupled set of algebraic equations analogous to PFR dif-
                                ferential equations must be solved.


                                                                                             (16-28)

                                Rearranging yields

                                                          F. -F.  = -r.V                     (6-29)
                                                           10
                                                                      J
                                                                J
                                     Recall that rj in Equation (6-16) is a function (A) of the species concen-
                                trations
                                                        4
                                                    r. = 1 = fj(C&?  ..., CN)                (6- 1 6)
                                                           'ij
                                                    J
                                                        i=  1
                                After writing a mole balance on each species in the reaction set, we substitute
                                for colncentratious in  the respective rate laws.  If  there is no  volume  change
                                with  reaction,  we  use  concentrations,  Cj, as  variables.  If  the  reactions  are
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