Abstract: A liquid cyclohexanone oxime A is vaporized by heating to obtain a cyclohexanone oxime gas A1 and the remaining residue C is distilled under a pressure lower than the pressure upon vaporization by heating, and then cyclohexanone oxime A2 contained in the residue C is recovered.

Abstract: A method is provided for evaporating cyclohexanone oxime in which cyclohexanone oxime is evaporated using a falling-film evaporator with wetting the evaporation surface of the evaporator well with the cyclohexanone oxime at a pressure of less than about 1060 Torr with a falling rate of the cyclohexanone oxime of about 170 kg/hour or more per one meter around the circumference of evaporation surface at the lowest part of the evaporator. In this method, the cyclohexanone oxime is evaporated efficiently with little decomposition thereof, while preventing the plugging of the pipes of the evaporator and continuously carrying out the operation of the evaporator for a long period of time.

Abstract: A method is provided for evaporating cyclohexanone oxime in which cyclohexanone oxime is evaporated using a falling-film evaporator with wetting the evaporation surface of the evaporator well with the cyclohexanone oxime at a pressure of less than about 1060 Torr with a falling rate of the cyclohexanone oxime of about 170 kg/hour or more per one meter around the circumference of evaporation surface at the lowest part of the evaporator. In this method, the cyclohexanone oxime is evaporated efficiently with little decomposition thereof, while preventing the plugging of the pipes of the evaporator and continuously carrying out the operation of the evaporator for a long period of time.