Environmental Engineering Reference
In-Depth Information
O N +1
V'
V"
O 1
1
20
V
Figure 5.16
O N +1
O 1
1
2
V 0
Figure 5.17
(b) For point
2 as the
min point, the operating line is
2 O N + 1 . Repeat procedure to
find V 0 /
O N + 1 .You will see that in this case, V 0 /
O N + 1 is larger .
As the
min point moves toward point V 0 , the ratio V 0 /
O N + 1 will increase but it is
still the minimum that we use. Since the actual V 0 /
O N + 1 is a multiple of the minimum,
we need to make sure that the actual value will not cause a pinch point anywhere in the
column.
5.7.2
Case 2: Tie-lines slope downward to the right on the equilibrium diagram
(Figure 5.17)
Again,
2 correspond to two pinch points. Follow the same sequence as for
Case 1 to find the mixing points corresponding to
1 and
1 and
2 .
The ratio V 0 /
O N + 1 for
2 . is larger than the ratio obtained using
1 .As
min point
moves away from point V 0 , the ratio V 0 /
O N + 1 will increase butitisstill the minimum
that we use to insure that the actual value that we use does not cause a pinch point in the
column.
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