Batch Refining Process
The system is designed for Batch refining capacities below 30 TPD in 3 batches per 24 hours consisting of neutralizing, bleaching, and deodorizing. Batch neutralizing comprises of treatment of oil with phosphoric acid, alkali, and water washing to remove gums and free acids. Bleaching i.e. treatment of oil with bleaching earth is carried out at controlled temperature and vacuum for pre-determined retention time, followed by filtration. This step will generally produce oil with lower levels of residual phosphatides and colour pigments. The next stage is deodorizing, which is used for deodorizing bleached oils with high temperature and vacuum followed by cooling in the heat exchanger.
- Flexibility in operation
- Controlled oil losses
- Easy operation
- Low maintenance
Degumming is a chemical refinery process used to remove sediments and phosphatides from the oils by adding hot water and separation of gums by centrifugal separator.
Types of Degumming
- Water Degumming: Water Degumming is first step in the edible oil refinery process. Oils contain hydratable phosphatides which absorb water.
- Acid Degumming/Gum Conditioning: Non-hydratable gums require use of acid to convert hydratable gums for complete removal of gums from oil. This process is mostly followed by alkali refining with advantage to reduce the consumption of bleaching earth in bleaching section.
- Enzymatic Degumming: In enzymatic degumming, the enzyme action eliminates the emulsification properties of the gums. The oil saving is proportional to phosphorous (gums), in ratio of 1:2 (1 oil) & (2 gums)
- Flexibility in operation
- Low Oil Loss
- Easy Operation & Easy start-up & Shutdown
- Low Maintenance
- Easy operation with or without automation
This process is used to remove the balance phosphatides and free fatty acids by using the acid and base lye in the form of soap stock by using centrifugal separators. Soap traces will be removed by addition of hot water and separation by centrifugal separator. These are no longer soluble in water and can be removed easily by decantation or centrifugal force. The removal of the free fatty acids does not close neutralization, as the operation also eliminates the phospholipids that are not hydrated at degumming level, and it reduces the amount of metal traces as well as some pigments and minor constituents. Oil is then dried by a vacuum dryer.
- Continuous process which allows heat recovery for reduced energy costs
- Effective for varying capacities
- Variable reaction temperature and retention time
- Temperature control for each step of the process
Water Washing & Drying Process
The residual soap in the degummed & neutralized oil is reduced by water washing. In this case, oil from separator is heated to about 95°C in the Washing Heater and then mixed with 10 – 15% soft water in the Wash Mixer. After a few minutes of retention the wet oil enters the Wash Water Separator. The washed oil, typically containing under 100 ppm soap and with a reduced level of phosphorus, is sent directly to bleaching as described above. The heavy phase soapy water is collected in the recovered oil tank and drained for effluent treatment.
Washed oil is fed continuously to the Vacuum dryer and sprayed through specially designed nozzles. The vacuum dryer is kept under a vacuum of 70 torr. The dried oil from the vacuum dryer is continuously pumped to intermediate storage tanks.
- Water-washing or special sorbents are used to reduce the residual soap in the neutralized oil.
- Minimal waste water is generated when special sorbents replace water-washing.
Pre-Treatment & Bleaching Process
This process us suitable for chemical as well as physical refinery process. It is used to remove the colour pigments, traces of soap by addition of bleaching earth under vacuum at prescribed temperature and retention time. Filtration of oil is done by Vertical Pressure Leaf Filters followed by Polish Filters.
The oil is then discharged into the slurry mixer above the bleacher. A valve dosing system proportions bleaching earth. The bleaching earth is introduced under the oil spray in the mixing chamber for improved mixing so that bleaching earth does not enter the bleaching vacuum system. The oil is heated up to bleaching temperature in the first compartment of Bleacher. The bleaching earth adsorbs any residual gums as well as trace metals, colour bodies and other polar impurities. Bleacher has multiple agitated compartments and operates under vacuum to ensure complete moisture and air removal. The dried oil and spent earth mixture is pumped to one of the filters where the spent earth is removed. The filtered oil is collected in the filtrate receiver.
- Reduced bleaching earth consumption
- High, uniform product quality assurance
- Maximum oil recovery from filter cake by steam blowing
This process is used to remove volatile matters and free fatty acids at high temperature and high vacuum to give stability and shelf life of edible refined oil.
Stripping:The hot oil enters the Packed Column, which is filled with special structured packing so that the oil is distributed into a thin film and is evenly agitated by stripping steam flowing counter currently from the bottom of the column. As a result, free fatty acids and other remaining volatile impurities in the oil are evaporated and removed with steam. The residence time in the column is only a few minutes. The bulk of the free fatty acids along with aldehydes, ketones, etc. in the oil are quickly stripped off before any heat induced permanent damage has been done.
Cooling:The deodorized oil is discharged into the Deodorizing Economizer and cooled by incoming oil. The oil is then discharged and further cooled to storage temperature in the Deaerating Economizer and Product Cooler. Anti-oxidant is mixed with oil in the Deodorizing Economizer. The finished oil is finally sent to storage via product filters.
Distillate Recovery: Fatty acids and other materials, evaporated from the oil, are condensed by contact with recycled and cooled distillate in the Vapor Scrubber. The distillate is circulated to the Distillate Cooler where it is cooled by cooling water. Accumulated distillate is discharged from the Scrubber to storage.
- Peroxide Destruction
- Color Destruction
- Odor and flavour removal
- Highest deodorizing efficiency
- Minimum fouling factor
Dewaxing process / Winterization process
Post the above processes, dewaxing of oil is done by cooling tower water followed by chiller. A proper residence time is given to have appropriate crystal growth in crystallizer. After the waxes get crystallized the oil is subjected to filtration. This dewaxed oil passes the cold test which gives clarity to oil even at low temperatures.
This process is used to remove the wax by cooling the oil up to prescribed temperature to form the wax crystal and by membrane filter. The process by cooling and Filtration is comprised of sequential cooling of bleached oil and then filtration. This process is easy to undertake however crystallizer design plays a very important role.
Sunflower, corn, canola and rapeseed oils contain non-triglyceride compounds that create a haze or wax in the oil when chilled or stored for long periods. Chilling followed by filtration that removes these compounds.
- Dewaxing by sequential cooling of bleached is oil followed by filtration
- Incorporating innovative and workable Crystallizer designs.