Cashew Nut Shell Liquid (CNSL) or Cashew Oil or Cashew Nut Shell Oil is a dark reddish brown viscous liquid, extracted from a soft honeycomb structure inside the cashew shell. It is a natural and renewable biomaterial. Thus, it offers much advantage over synthetics. CNSL is often considered as cost effective and better modern materials for unsaturated phenols. Cardanol is basically a monohydroxy phenol with a long carbon chain in the meta-position. It has the potential as a substitute for phenol in resin phenolic-based chemical products. Main Process of Cardanol extraction from Natural CNSL comprises the conversion of natural CNSL into technical CNSL in which anacardia acid is de-carboxylate into cardanol.
Cardanol is distilled from Cashew Nut Shell Liquid. Cardanol can be manufactured in batch or continuous distillation process. A batch of Decarboxylated CNSL is heated to 250°C under high Vacuum in a reactor. After removal of initial impurities such as water and other low boilers Cardanol distillation begins and the vapour that is getting evaporated under vacuum is collected in a condenser and condensed with the right utilities and collected in receiver.
Technical CNSL is obtained mainly from cardanol (60–65%), cardol (15–20%), polymeric material (10%), and traces of methyl cardol. Cardanol is sent to distillation for further purification.
Vacuum plays an important role in the evaporation process. Now days, water ring pump (WRP) is used in this process but these vacuum systems require lot of water as sealant fluid that circulate inside pump casing and in every minute process carry over contaminates the sealant water that’s why there is need of change of sealant water at regular interval of time. The treatment of waste water generated from WRP becomes difficult to treat and that makes the process less economical.
Everest Dry Screw vacuum pump has been used successfully in this process, No water contamination occurs as no sealing fluid is required that makes the process economical and keeps the environment clean. Automated scheduled flushing cycles are performed with suitable solvent at regular intervals to make the system maintenance free, hence adding value to the complete supply chain.
