Pre Treatment The feed oil is heated to 65-70°C in the Economiser by outgoing deodorized oil followed by feed heater in batch refinery (during start up). Concentrated phosphoric acid (0.05 - 0.10%) is injected by the Acid Metering Pump and intensively mixed with the oil in the Acid Mixer before entering the Conditioning Reactor. The oil is discharged into the slurry mixer above the Bleacher. These process is done through batch refinery
Bleaching The Pre-treated oil is pumped in to the Bleacher vessel which is kept under vacuum, and heated up to Bleaching temperature under continuous mechanical agitation. The calculated quantity of bleaching earth is charged to Bleacher under oil level in order to avoid earth entry to the bleaching vacuum system. The earth adsorbs any residual gums and soap as well as trace metals, color bodies and other polar impurities. The Bleacher has mechanical agitator operates under vacuum to ensure complete moisture and air removal. The dried oil-earth mixture is discharged to the Filters with the help of pump, where the spent earth is removed.
Filter Management: The bleaching system is based on the use of one filter of sufficient filtration area. This filter can separate bleaching earth, which is equivalent to two batches of bleacher. After completion of filtration filter is being cleaned and prepared for the next cycle. The cleaning procedure begins by first pressurizing the filter with steam to expel residual oil into the Recovered Oil Tank and dry the spent filter cake. The oil recovered from the filter cake is collected in the tank and can usually be recycled to the Bleacher. After drying, the filter is opened and the spent cake is dislodged and discharged via a hopper. The filter is then closed and readied for the next batch.
De-Acidification / Deodorization The Feed Pump pumps bleached oil to Deodorizer from the Intermediate Bleached oil Tank through heat exchanger cooler if offered. The oil is heated up to full processing temperature by thermal fluid or high pressure steam in the Deodorizer vessel operated under full vacuum under continuous sparging steam. As a result, free fatty acids (formed because hydrolysis) in the oil and other remaining volatile impurities will be flashed off with the steam as the oil temperature increases. The oil is maintained at this temperature under full vacuum and sparge steam for 3-4 hours. The prolonged thermal action breaks down carotene and other color bodies, resulting in a lighter oil color. Also, the amount of remaining free fatty acids in the oil is reduced to an absolute minimum. The stripping steam and resulting vapor from the Deodorizer is routed through the catchall. Accumulated distillate is discharged (drained) from the catchall at the interval of cycle.
Cooling The deodorized oil is dropped by gravity to heat exchanger-cum-cooler or cooled inside the deodorizer .In the heat exchanger-cum-cooler if offered; cooling of the oil is done by feed bleached oil circulated through coils provided. Further this oil is cooled to the moderate filtration temperature and pumped to storage tank through the polishing filters.