Diffuser dynamic model - wits.ac.za · PDF file•Elements of a diffuser •Operating...
Transcript of Diffuser dynamic model - wits.ac.za · PDF file•Elements of a diffuser •Operating...
© SMRI 2014
Diffuser dynamic model
Industry Representative:
Dr Richard C Loubser
© SMRI 2014
content
• Background - Extraction of sugar • Elements of a diffuser • Operating constraints
– Flooding – Dry bed operation
• Context of problem – Changes in operation – rerouting of pipe flows – Operational practices – pumps etc. – Training
• Desired outcomes
© SMRI 2014
Extraction of sugar
© SMRI 2014
Elements of a diffuser
© SMRI 2014
Elements of a diffuser
© SMRI 2014
Operating constraints
• Sucrose in plant cells – Diffusion
• time dependent
• concentration gradient
• wetting
• Sucrose on fibre surface – Washing (Lixiviation)
• mixing
• juice velocity
• wetting
© SMRI 2014
Operating constraints
• Flooding
– Bypassing of stages
– Mixing of concentration profiles
– Loss of juice
• Dry bed operation
– Poor contacting of sugar cane and juice
– Loss of extraction
– Operators seldom act
© SMRI 2014
Context of problem
• Change of configuration – Reduce residence time
– Improve wetting of cane – control recycle
– Improve juice quality
• Operational practices – Model consequences of actions such as stopping
pump to cure flooding
– Procedure for priming of pumps
• Model based training – Show operators consequences of interventions
© SMRI 2014
Desired outcomes
• Modelling of filling and draining of cane bed – Juice introduced through spray at surface – Juice spreads out as it enters bed – Juice migrates through bed – Juice interacts with adjacent sprays
• Modelling of delay factors – Trays – Heaters – Pumps – Pipework – Drying mills
© SMRI 2014
Bonus outcomes
• Prediction of extraction
– Juice velocity
– Concentration difference
© SMRI 2014
Outcomes
© SMRI 2014