06/12/2022
Continues chemical Refining for edible oil.
“Why, When & When Not”
INTRODUCTION:
Refining of Crude Edible Oil is practiced as a purifying treatment designed to remove free fatty acids, phosphatides and gums, coloring matter, insoluble matter, settlings, and miscellaneous unsaponifiable materials from the Crude Oil. It is required because when the oil is heated in subsequent processing operations, these impurities can cause the oil to become colored, to foam, or to become cloudy because of precipitated solids. This is called “Chemical Refining”.
CHEMICAL REFINING:
Practically all edible oils are refined with some type of alkali, usually caustic soda solution is used. It can be done in a batch process, or a continuous system. The addition of an alkali solution to crude oil results in chemical reactions and physical changes. The alkali combines with the free fatty acids present in oil to form soaps; the phosphatides and gums absorb alkali and are coagulated through hydration or degradation; much of the coloring matter is degraded, absorbed by the gums, or made water-soluble by the alkali; and the insoluble matter is entrained with the other coagulable material. If excess caustic is used, prolonged exposure to heat will result in saponification of the oil, with resultant higher oil losses.
CONTINUOUS VS BATCH REFINING:
If the batch wise refining and the continuous refining with centrifuges are compared, the following can be observed:
1. The batch wise refining takes place in a simple inexpensive apparatus which requires little maintenance. The continuous centrifugal refining, however, requires considerable investment and good maintenance service..
2. The setup for the batch wise refining is highly flexible and can therefore process oils of widely divergent quality. The refining with centrifuges on the other hand requires oils of constant quality & .in abundance. Adjustment of the apparatus when changing from one type of oil to another is generally not simple and is a main disadvantage of the continuous refining methods.
3. On the other hand the influence of the operator on the results of processing and losses in the batch process is very great. In the centrifuge process it is much lessened, although the adjustment of the apparatus requires highly skilled labour.
1. Types of Oils being processed.
If you are processing oil in bulk, say 100 tonnes per day or more. You should opt for continuous refining process.
2. Quality of Oil being processed.
If your oil has high FFA say above 2%, continuous refining process will yield better results. The condition at (1) stands
3. Quantum of Production.
If you are processing two or more than two oils, with FFA upto 1% and your production requirement is around 50-60 tonne per day, it will advisable that you resort to Batch processing. The continuous refining will cost you more in terms of utilities and plant operation.
