Page 352 - Water and wastewater engineering

ION EXCHANGE 8-21

TABLE 8-3
Typical range of design criteria used in sizing ion exchange columns and vessels
Parameter Range of values Comment
Pressure drop 35–70 kPa 135 kPa maximum
Diameter (D) 2.5 m Fiberglass tanks
3.6 m Steel tanks
Height (H) of resin 0.9 m To avoid premature breakthrough
and 4 m To limit pressure drop
H:D of resin bed 1.5:1 to 3:1
Expansion of resin bed 100% Typically 50%
Height of column height 4 m Use columns in series for greater height
Sources: GLUMRB, 2003; Gottlieb, 2005; Reynolds and Richards, 1996.

Example 8-4. Design the tank for the Hard Times ( Examples 8-2 and 8 -3 ) ion exchange col-
umn. The following design parameters have been established for the initial trial design:

3
Resin shipping weight moist) 800 kg/m
(
Solution:
a. The Solver* program in a spreadsheet was used to perform the iterations for solution of
this problem. The spreadsheet cells are shown in Figure 8-7 . The values shown in the
figure are the final solver solution. The cell locations used in the figure are identified
by brackets [ ] in the discussion below.
b. Begin with the input data by setting the following:
3
[B5] Q 275m /d (from Example 8-2 )
[B6] Resin mass 750 kg (on moist basis from Example 8-2 )
3
[B7] Shipping weight 800 kg/m (on moist basis given in the problem statement)
2
3
[B8] Surface loading rate 408 m /d · m (Any rate between 400 and 800 may be se-
lected as the starting point. The value shown here is the first guess. The value shown
in the spreadsheet is the final Solver value.)
c. Compute the volume of the media in cell [B13] as

[B6 ] 750 kg 3
094 m
.
[B7 ] 800 kg/m 3

®
*Solver is a “tool” in Excel . Other spreadsheets may have a different name for this program.