Second-Order Reactions with Unmixed Feed

5 Second-Order Reactions with Unmixed Feed 

Cellsdend + 7, j - jin + 1) = Suml / Sum2 Mixing cup average Next j 

Loop stop manually based on observing the outlet concentration on the spreadsheet End Sub 

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Patterson, G. K. (1973). Model with no arbitrary parameters for mixing effects on second-order reaction with unmixed feed reactants, in Fluid Mechanics of Mixing, E. M. Uram, and V. W. Goldschmidt, eds., ASME, New York, pp. 31-38. 

Figure 13 shows an example of results obtained with the lEM-model in a CSTR for zero-order and second-order reactions (unmixed and premixed feed). The following conclusions can be drawn from such simulations ... 

With this object, we have chosen experimental conditions in which micromixing effects were expected to be a maximum i.e. a continuous stirred reactor and a rapid liquid phase reaction close to zero order with unmixed feed of reactants. Experimental parameters were adjusted to such values that the space time, the reaction time and the micromixing time was of the same order of magnitude, ranging from 1 to 10 seconds. Micromixing effects were thus clearly and reliably observed. 

To quantify the effect of the incomplete mixing on reaction rates in the front of the reactor channel, this same simulation was repeated assuming second order kinetics (first order in each of the two components) and Cjj = C2j = 100 mol m. A rate constant of 1.0 X 10 m moh s was used to give an intermediate level of conversion (near 25%). This case can be compared with a simulation in which the inlet boimdary conditions were changed to assume complete mixing (50 mol m of each component across the entire inlet cross section). The axial fractional conversion profiles for these two cases (unmixed and premixed feeds) are shown in Fig. 13.4, where the unmixed feed curve is the average of the calculated values for the two components. The computed conversions for the two components were... 

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