Batch distillation at total reflux
- Start the model Batch distillation column with default parameters (6 trays+boiler, water-ethanol mixture, ethanol mass fraction 25%)
- Fill the boiler with feed product up to 90% level
- Set heat in manual with DPIC output at 70%
- When the product reach boiling temperature, decrease heat input to 30%
- Look at column and tray inventory (click on )
- Look at Mac Cabe and Thiele graphic construction
- When liquid-vapor circulations are establish, wait to reach steady state
- Increase heat input while looking at tray inventories, and check what column ΔP leads to column flooding
- Stop heating the column and wait for trays being empty
- Send bottom product to residue tank and verify mass balance.
Batch distillation with variable reflux
The objective is to distillate about 2000 kg of a water-ethanol mixture with ethanol mass fraction of 25%, and to obtain a distillate at more than 90% of ethanol, a residue at less than 0.5% of ethanol, and an intermediate fraction (we could also set a spec for it but we don't).
- Start the model Batch distillation column with default data (6 trays+boiler, water-ethanol mixture, ethanol mass fraction 25%)
- Fill the boiler until the interlock close the check valve
- Put the column at total reflux with heat input in manual at 30%
- When overhead product ethanol mass fraction reach 90%, start draw off distillate at reflux ratio of 2
- Increase reflux ratio during the distillation to keep distillate at ethanol specification of 90%
- Change distillate drum when level reach 70-80%
- Send distillate fractions to the final distillation tank
- When the reflux ratio reach 8, change distillate drum and start inter-fraction at reflux ratio of 1
- When you estimate that boiler is low enough in ethanol, and tray inventory will not increase global residue up to 0.5%, stop heating the boiler. You can look at composition profiles to help you
- When trays are empty, send boiler mixture to residue tank, and inter-fraction to recycle tank
- Verify global and ethanol mass balance
- Calculate distillation yield
Remark: you can also put constraint on inter-fraction composition, and/ot try to distillate with minimal energy consumption