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54                                 Conversion and Reactor Sizing   Chap. 2

                              Example 2-7  Comparing the Order of  Sequencing Reactors

                              Calculate the individual reactor volume as well as the total reactor volume for each
                              scheme in Figure 2-6 for the reaction data given in Table 2-2 when the intermediate
                              conversion is 50% and FAo = 0.867 mol/s.

                              Solution
                              We again use Figure 2- I  to arrive at Figure E2-7.1 and evaluate the design integrals.


                              Scheme A

                                               dX -
                                                  -
                                   Plug flow:  FAO 8 -rA
                              Integrating between X = 0 and X = 0.5 yields





                                                              4        1
                                          -
                                          -
                                               0.25
                                          =&a-     [189+4X211+303]
                                                3
                                          = (O.867)( 11 1)
                                          = 97 dm3 (liters)

                                                     x, - XI
                                    CSTR:     V, = FAo - 0.867(0.8 - 0.5)(800) = 208 dm3
                                                            =
                                                       -
                                            V,,,   = V, + V, = 305 dm3

                                               Scheme  A                   Scheme  B
                                   1000

                                   800
                              -
                               ill
                                    600
                               €E
                               W
                               -1  ,Q  400
                                I
                                    200

                                                                                            0
                                      0
                                               Conversion,  X             Conversion,  X
                                                         Figure E2-7.1
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