Continuous dehydration of Ionic Liquids in a falling film evaporator

• Water was removed from an Ionic Liquid water mixture using a falling film evaporator.
• The experiments were carried out in continuous operation mode of the evaporator with different feed rates.
• Resulting water contents after the separation were about 0.01 gwater/gmixture.
• The film heat transfer coefficients were calculated using experimental data and compared to models from the “VDI-Wärmeatlas”.

Water is a commonly found impurity in Ionic Liquids (IL), which may be critical for many applications due to the changes of the ILs’ physical properties. A falling film evaporator operated in continuous mode is used to separate water from IL/water solutions and determine favorable process parameters. The dehydration was investigated for two different IL at different feed rates and water concentrations at the inlet. Water contents from 0.0086 to 0.0121 gwater/gtotal were achieved. Additionally, the thermal performance of the evaporator was assessed resulting in film heat transfer coefficients on the evaporation side ranging from ∼1000 W m−2 K−1 to ∼1800 W m−2 K−1 calculated according to VDI Wärmeatlas.