The methanol rectification unit is designed to distillate water and methanol starting from wet methanol streams coming from upstream process units.
Methanol vapour is recovered from the top of distillation column, condensed and further cooled, while water is discharged from the column bottom to the recovery heat exchanger where it is cooled with the column feed.
Both streams are then reprocessed into biodiesel plant.
The advantages of Desmet Ballestra Methanol Rectification Unit are mainly two:
The recovered methanol is so deeply dried that it is totally re-used as reagent of transesterification reaction with a consequent important reduction of its consumption as OSBL required chemical.
The distilled water contains methanol in so negligible traces that it is totally recovered as process water to prepare citric acid solution reducing the OSBL utilities consumption.
Distillation tray column design is well optimized to ensure a zero waste unit for both liquid and gaseous effluents.