Rotary distillation and steam distillation are two different distillation methods, and have their respective advantages and scope of application. If the rotary distillation is to be used, the evaporated sample must be placed in a rotating cylinder at the bottom and heated with water bath.
When heated, the rotating steam bottle rotates under the motor, thus dispersing the solution continuously on the bottle wall, which increases the evaporation area and increases the evaporation rate. Rotary distillation is often used in conjunction with pressure relief equipment to reduce the pressure in the system by using a vacuum pump, thus reducing the boiling point of the liquid and making it easier to evaporate.
When steam distillation, the water vapor into the mixture containing volatile substances, in the phase of the vapor phase contains vapor and vapor phase of the total pressure equal to the vapor pressure and component partial pressure. When the total pressure of vapor is equal to the external pressure, the liquid is boiling at a temperature far below the normal boiling point of the component, and the components are steamed out with the steam.
In the operation of steam distillation, the water vapor mainly plays the role of heat-carrying body and lower boiling point. In principle, any gas or vapor not miscible with the liquid can be used, but because the water vapor price is easy to get, after cooling easily separated so more. For higher-boiling solutes, superheated steam is often used as a heat source, and can sometimes be used in conjunction with pressure relief equipment to reduce the boiling point.