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

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

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

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

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

Sugar end feed materials

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??

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

Example color 92 purity Need 4500 color 1st masse for 45 color sugar Color/NS ratio 12000/(100-92) = st 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

4 boiling scheme for extract

Sugars™ model validation

Extract boiling scheme options

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

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

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