Stirred dead space

Modify the program to allow for zero dead space volume and study the effect of fractional by-passing only. Compare the results to that of a perfectly stirred tank. 

P5.04.02. STIRRED TANK WITH BYPASS AND DEAD SPACE... 

Insufficient mixing may easily result in a low nitration rate owing to the small interfacial area. It can also lead to a non-uniform nitration process. Owing to inadequate construction of the stirrer, too low a speed of rotation, or an interruption in stirring, so-called dead spaces may easily be formed in which non nitrated or not fully nitrated substances accumulate. If a rather large quantity of the mixture is stirred suddenly, rapid extension of the interfacial area takes place, followed by the generation of large amounts of heat and a rise in temperature. This may cause a spontaneous decomposition of the reaction mass in the nitrator, and then an explosion. 

Fig. IV. 1. Typical apparatus for studying gas reactions. Note A stirring device operated magnetically may be used inside the reaction vessel. Also, the connecting tubing may sometimes be wound with nichrome heating elements to prevent condensation of less volatile vapors and reduce the effective volume of the dead space. The use of too small or too long capillary tubing is restricted by the difficulty of evacuating the reaction vessel, which increases with longer or smaller capillary leads.

Figure I2.5.b-l Model of real stirred tank with bypassing and dead space.

Corrigan, T. E. and W. 0. Beavers. Dead Space Interaction in Continuous Stirred Tank Reactors. Chem. Eng. Science 23 (1968) 1003. 

Some approximate methods have been applied previously to deal with the inhomogeneous nature of flow patterns in stirred tanks [67, 68]. Koh [67] divided the stirred tank into three compartments, the impeller zone, the bulk zone and a dead space, and assigned different shear rates for each compartment. Furthermore, Koh et al. [69] ignored the dead space, but split the impeller zone into impeller tip zone and impeller zone. Ducoste [68] essentially followed the same approach, dividing the suspension volume into two zones, the impeller discharge zone and the bulk zone. 

---