Cane Sugar Refining - Purolite

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Cane Sugar Refining with Ion Exchange Resins
9. Resin Backwashing
Resin backwashing is carried out by an upflow of demineralized water preferably at the
same temperature as the feed syrup. The flow should be slowly introduced to prevent
the resin from rising in the column as a plug. When the resin is fully fluidized the flow
should be adjusted to expand the bed by 75% and be continued for 15 minutes. After
stopping the backwash flow the bed should be allowed to settle, drained to just above
the bed top and the bed height measured and recorded.
10. Resin Regeneration and Rinsing
The resin regeneration should be carried out in four steps:
a) 2.0 BV of 10 % NaCl at 1 – 2 BV/hour at a dosage of 200 g/L with 0.5 % NaOH
(10 g/L resin) (60 to 90 minutes)
b) Rinse using 2 BV of condensate at 1 to 2 BV/hour flow rate. (45 – 60 minutes)
c) Rinse using 5 BV of condensate at 10 – 20 BV/hour. (15 – 30 minutes)
The regenerant flow rate should be carefully controlled to achieve even flow through the
bed. A reservoir of regenerant should be maintained above the resin bed top.
To obtain useful design data samples of regenerant may be taken periodically and
analyzed for the components of interest. The time when the concentration of the color
bodies in the solution has reduced to insignificant levels should be noted.
The bed height should measured and noted at the end of each of the above steps.
11. Number of Cycles
The above procedure should be repeated using the same anion bed for a sufficient number
of cycles to achieve equilibrium and to observe the extent of any fouling of the resins.
If fouling is observed or if cycle times are observed to decrease from cycle to cycle then
Purolite will advise what action should be taken. This will normally involve modifying
the regeneration procedure using dilute HCl solution (cross regeneration).
12. Application of Test Data
The results from the above tests will demonstrate the anion decolorization process and
will provide a guide for the design of the next scale of operation for syrup decolorization.