Page 485 - Elements of Chemical Reaction Engineering Ebook
P. 485

456                       Steady-State  Nonisothermal Reactor Design   Chap. 8

                             and therefore we can solve Equation (E8-6.7) for the equilibrium conversion
                                                              KC
                                                        x, = -                        (E8-6.13)
                                                             l+Kc

                             Solution by Hand  Calculation (you probably won't  see this in the 4th edition)
                             We  will now  integrate Equation (E8-6.8) wing Simpson's rule after forming a table
                             (E8-6.1) to calculate (FAo/-rA)  as a function of X. This procedure is simiiar to that
                             described in Chapter 2. We  now  carry out a sample calculation to show how Table
                             E8-6.1 was constructed, for example, at  X = 0.2.
                             (a)   T = 330+43.33(0.2)  = 338.6 K
                                            [    ((360N338.6) j]
                             (b)   k  = 31.1 exp  7906  338'6-360   = 31.1 exp(-1.388)  = 7.76h-I


           Sample calculation   (c)                              = 3.0~~~-0 = 2.9
                                                                          0412
             for Table E8-6.1     Kc = 3.03 exp
                                        2.9
                             (d)  X, = - = G.74
                                      1 + 2.9
                                                                            mol       kmol
                             (e)   -rA  = fT)(9.3)$   [I - [ 1 + &)(0.2)]  = 52.8 - 52.8 -
                                                                                 -
                                                                                -
                                                                           dm3. h     m3.h
                                  FAO - (0.9 mol butane/mol tota1)(163. kmol total/h) - 2.778 m3
                             (0   --                                       -
                                                         kmol
                                  -rA                52.8 -
                                                         m3. h
                                                TABLE  E8-6.1,  HAND CALCULATION
                                 X    T(K)  k(h-')    Kc      x,   -rA(kmol/m3. h)   - (m3)
                                                                                   - rA
                                0     330     4.22    3.1    0.76       39.2         3.14
                                0.2   338.7   1.76    2.9    0.14       52.8         2.18
                                0.4   341.3   13.93   2.73   0.73       58.6         2.50
                                0.6   356.0   24.21   2.51   0.12       37.1         3.89
                                0.65   358.1   21.14   2.54   0.715     24.5         5.99
                                0.7   360.3   31.61   2.5    0.11        4.1        35.8



                                                                                      (E8-6.14)

                             Using Equations (A-24) and (A-22), we obtain
                                  3                                  0.1
                              V = -(0.15)[3.74  + 3(2.78) + 3(2.5) + 3.891 m3 + 7 [3.89 + 4(5.99) + 35.81 m3
                                  8
                                = 1.32 m3+2.12 m3
                             F   3   r   l
   480   481   482   483   484   485   486   487   488   489   490