The physical refining process

This paper deals with influences and optimizing of changing process conditions for physical refining of palm oil. These process variables are temperature, pressure, residence time, fluid flow and stripping steam to oil ratio. These parameters influence not only finished oil quality, oil yield, energy consumption and running costs, but also content and yield of natural stabilizers like tocopherols or color compounds like carotenes, and last, but not least, environmental load of waste water and exhaust air as studied under industrial plant conditions. With the right pretreatment process physical refining of palm oil is not only much more economical than chemical refining in connection with stripping steam deodorization, but also causes much less pollution by waste water and exhaust air. Under all these aspects the performance of continuously operated industrial plants now in use for physical refining of palm oil is being examined. Because of the water solubility of the low‐boiling thermal degradation products, the effluents of nearly all installations must be specially treated to fulfill today's legal requirements on BOD and on COD as well as on oil and grease content. The only exception is a new counter‐current two‐step film type physical refining process in connection with a combined sophisticated steam ejector vacuum and two‐step exhaust air washing system, with which, without any air pollution, COD values of <50 for waste water are possible. For best oil quality deacidification should be done with pressure drop of less than 1 torr at 2 to 3 torr tap pressure at 260 C working temperature with residence times of 10 min and counter‐current exchange efficiency of 6 to 8 theoretical plates.