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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