Importance of in-line colour measurement of sugar

for product quality and factory performance

By Tim Diringer and Bjarne Christian Nielsen

Copyright Neltec 2012

20 Years ago the first colour measurement has been installed in

the Danish Assens factory

Today more than 100 instruments are installed all

over the world

Definition of process control

Process control is the method to keep the process and the quality of the final product inside the targets, by controlling and regulating various process parameters

Definition of process control

Process

product

input

Influencing parameters

Online data collection in a sugar factory

Diffuser: Temperature, flow rate

Purification: pH, level, temperature, turbidity, colour

Evaporators: Temperature, pressure, level

Crystallisation: Temperature, pressure , level, density

Centrifugals: ???

Control, alternator,699, 700- boiler, 643, 644, 647, 656- cane throughput, 76, 166- chemical, 577 – 600- clarification, 227, 228, 236- condenser, 330- conveyor, 74-76- crystallizer, 417- diffuser, 160, 165 – 168- evaporator, 300, 301- flocculant addition, 349- juice flow, 199- mill, 141-144- pan boiling, 388-398- rotary drum filter, 248, 257, 258, 260- sugar dryer, 479- turbine, 700

Peter Rein, Cane Sugar Engineering page 755

centrifugation

Sugar massecuite

Spray waterLayer thickness

• Leaving syrup on the crystals reduces pol, increases ash and leads to caking

• A combination of the two above (very common)

How centrifugals influence sugar quality

The centrifugals influence the sugar quality and the mill profit in 3 ways:

Overwashing dissolves good sugar, generates more molasses and decreases capacity

Nowhere in processing

can so much sugar

be lost so quickly

and with so little notice

as in centrifugation

To avoid sugar losses the operator must see the result of the centrufigation process and act accordingly

Step by step to operational

measurements

Lab measurements

Lab measurements

time delay

Lab measurements

time delay

No information about origin of error

A factory with an output of 1200 t/d raw sugarproduces 50 t raw sugar per hour

50g of sugar are used for the analysis

This is 0,000050 % of the total amount of sugar

If a sample for determing the colour in soloutionIs taken every 2 hours

On-line measurement

fast results

no information about origin of error

On-line measurement of each batch centrifugal

tells something about origin of errors.

Measurement of a colour profile for each batch centrifugal

pinpoints the origin of the error

very operational

The instrument

The Neltec ColourQ is the ideal tool to control product quality and to pinpoint process problems

Installation on a belt conveyor

installation on a screw conveyor

optimizing the centrifugals

1st step:

Get an overview of the centrifugal performance

2nd step:

learn to interprete the colour profiles

Colour of sugar in centrifugals 1 and 4 is 40 % higher

than the colour of sugar in centrifugal 3

Spray nozzles of centrifugal number 1 hve been replaced

Backing screen of centrifugal 4 has been washed

Improvements at Manildra-Harwood Mill

• Amount of sugar within the specs increased

Improvements at Manildra-Harwood Mill

• Molasses purity was reduced from 44 to 41

Improvements at Manildra-Harwood Mill

• The amount of massecuite required to produce 100 tons of sugar was reduced from 200 tons to 195 tons

To rely on the data collected inline, the following aspects must be fullfiled:

Accuracy of the instrument

Reliability of the calibration

Lab control in a refinery

To ensure product quality, in line measurement is necessary

In line colour measurement helps the operators to understand the

process

Time span from occuring to solving of a problem is reduced

dramatically

Capacity increases and sugar losses decrease

Conclusions

"To measure is to know"

(Lord Kelvin, 1883) 

Thank you for your attention!

Questions?