Drying and Cooling ( located at solvent free zone)
The desolventized and toasted meal is dried to have a moisture content below 12% by hot air passing into the drying zone. The meal temperature is around 65°C. The meal is cooled by cold air in the cooling section below 45°C.
The levels in bottom compartment in DT section, drying and cooling section are controlled by the specially designed rotary valves which are operated by geared motors. The deoiled meal is conveyed by the mechanical conveyor to meal storage.
Miscella distillation section
Miscella from the tank goes to bottom of economizer. The miscella is heated by vapours of DTDC section. The heated miscella from the economizer, achieves the concentration from 20 % to 65 -70 %.
The concentrated miscella is conveyed to second evaporator where it is heated by fresh steam and is concentrated to 95%. The rich miscella of 95% is further conveyed to oil driers which are steam jacketed and operate under vacuum.
The traces of solvent are removed by introduced steam. The recovered crude oil is then conveyed to storage tank.
Hexane Recovery Section
The air space in the Extractor, Hexane water separation tank, Vapour contactor and DT condenser gets saturated with hexane. The incoming meal also carries nearly double the quantity of inflow of the material into the extractor This air gets saturated during travel in the system and has to be discharged into atmosphere after recovering the hexane.
All vapours are taken into the condenser, where its cooled by cooling water. The vapours are further sub cooled by cooling water at 6 to 8°C and hexane is recovered.
The air further goes to absorption tower, where mineral oil absorbs hexane. The mineral oil is heated to 90 to 100 °C before it enters the desorption tower. Further, absorbed hexane is desorbed in desorption tower. The mineral oil is kept in circulation and safety filter is provided to remove dirt from the oil.