1. Ratio of color to non-sugars Application to sugar end operations
Paul Fry & Phil Thompson
Sugar Knowledge International Ltd

2. What is the ratio color/NS ?
ICUMSA color divided by (100-purity)
Example color 90 purity thick juice, ratio color/NS = 300
A measure of the color strength in the impurities in solution
Increasing color/NS means more color is being formed as the NS quantity is constant

3. How can color/NS be used ?
For monitoring sugar end performance to identify areas where color is formed.
To develop boiling schemes appropriate for non standard materials such as MDS extract or juice from deteriorated beets

4. Color tracking in sugar end
Thick juice input 92.5 purity, 3000 color
Color/NS ratio of feed = /( ) = 400
Molasses output 60 purity, color
Molasses color/NS ratio = 1000
Color formation in sugar end 4001000 = 150% increase

5. Color formation in sugar end
White massecuite (A) %
Intermediate (B) %
Low raw (C) %
Easy to get color increase of 200% (3 times) from centre of above ranges
Low raw color increase can be avoided if a molasses separator operates on intergreen

6. Sugar end feed materials

7. What boiling scheme to use
If color/NS <400 standard 3 boiling OK
Low purity high color material can go to 2nd boiling (high raw, intermediate, B)
Cane raw would expect ~7 boilings to achieve low molasses purity
How to handle high purity high color feed ie high color/NS ratio??

8. Stepwise approach
Define 1st massecuite color required to meet sugar color spec - usually 100:1 ratio
Calculate necessary 1st massecuite purity using above and color/NS ratio
Calculate predicted high green purity from 1st masse purity and expected yield (50%)
Decide if high green purity is excessive
Introduce 4th boiling if needed to control purity of intermediate / high raw (B) pans

9. Example color 92 purity
Need 4500 color 1st masse for 45 color sugar
Color/NS ratio 12000/(100-92) = 1500
1st masse purity = /1500 = 97 pty
At 50% white sugar yield (% masse) calculated high green purity = 93.3
Calculated intergreen purity = 83.5
Problem for molasses purity and B CVP

10. 4 boiling scheme for extract

11. Sugars™ model validation

12. Extract boiling scheme options

13. Back-boiling alternative ?
Recycling intergreen (B runoff) back to B pan reduces massecuite purity
Knock-on is a reduced molasses purity
Intermediate or high raw sugar is the feed to the white pans, back-boil increases color
Recycling around a color forming stage increases color/NS ratio and makes it worse

14. Back-boiling Reduces molasses purity by 5 units,
increases sugar color 250%

15. Summary Color/NS is easy to calculate
Allows quick monitoring of color formation
Feed materials with higher color/NS ratio increase sugar color and/or molasses purity
Higher color/NS = more boiling stages
Higher color/NS = increases steam demand and total massecuite flow
Recycle by back-boiling increases color/NS and is not helpful to sugar color