Examples of Sequencing and Selection

We discuss two examples, for which presynthesis was made in the previous section. We accept equimolar feed composition for mixture acetone(l)-benzene(2)-chloroform(3)-toluene(4). One of the unstable nodes Ai is component 1. At 

Xb Regfi (xb2 = xb3 =xba = 0,333). Therefore, direct split in the first column 1  

4 is feasible only with preliminary recycle. Equimolar mixture of components 

4 can be accepted as a recycle. In this case, the necessary recycle rate is close to minimum possible. Such a split is one of the most preferable. In the first column, we obtain pure component 1 and zeotropic mixture 2,3,4 that can be easily separated in the second and third columns (sequences in Fig. 8.23a,b). 

The following split in the first column (indirect) 1,2,3 4 is feasible without any recycle because component 4 is stable node iV+ and face 1-2-3 is entirely filled 

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