Oil Refining means the conversion of crude oil for direct human consumption, edible processing, and industrial purpose. The crude oil obtained from expellers or solvent extraction contains impurities. To make the oil edible, the impurities must be taken out; such a process is called “Refining”.
VMT provides Turn-Key projects for all types of Edible Oil Refineries. VMT has handled many projects related to Chemical Refining, Physical Refining &Batch Refining. In the power generation sector, we deal with a variety of power plant projects, such as energy-saving combined cycles and large-scale power plants.
The refining process is carried out in various stages
• Degumming, Neutralizing, and Washing
• Bleaching
• Dewaxing
• Deodorizing
• Fractionation

DEGUMMING

The Degumming process involves dispersion of phosphoric acid/citric acid into the oil, allowing a contact time and then mixing lye in this acid–oil emulsion followed by 2-3 hrs of retention time. Then the resulting oil is passed to Centrifugal Separator where gums are removed from the oil.

NEUTRALIZING

In this process, caustic lye is added to acid-conditioned oil. It neutralizes free fatty acid, transforming FFA into soap. The oil is then passed to the Centrifugal separator to remove soap from the oil. This step also eliminates non-hydratable gums and metal traces.

WATER WASHING

In this process, crude oil is hydrated by mixing a calculated amount of water. Since hydrated gums are insoluble in oil, hence it gets precipitated. These hydrated Gums are then separated from the oil in Centrifugal Separator. In this stage, only hydratable gums are removed.

BLEACHING SECTION

In addition to color pigments, bleaching also removes residual phosphatides, metal contaminants, soaps, and oxidation products. Oil undergoes Pre-treatment with Phosphoric acid/citric acid and the pre-treated oil is given pre-determined retention before going to the Bleacher. This step splits soap and traps metal contaminants.
The pre-treated oil is mixed with bleaching earth in an inline static mixer, where oil and bleaching earth is formed before entering the Bleacher. The bleacher is equipped with mechanical agitation and steam spraying for better contact between oil and bleaching earth. Bleacher is kept under a vacuum of 710 mm Hg. A retention time of 40 – 60 minutes is given to slurry for efficient contact and adsorption of color pigments and other impurities onto the Bleaching earth. The slurry is then sent to Pressure Leaf Filters for filtration of bleaching earth from oil, followed by polish filtration. The spent cake is then dried by steam blowing to remove oil from it.

DEWAXING PROCESS

Oils like sunflower, corn, and rice bran contain waxes. A method of dewaxing a vegetable oil which comprises adjusting the temperature of vegetable oil containing wax to allow the wax to crystallize and subjecting the temperature-adjusted oil to filtration using a porous membrane having a critical surface tension of less than 33 dynes/cm and having an average pore diameter of 0.05 to 5 μm, thereby selectively permeating the vegetable oil through the membrane while separating the wax from the vegetable oil. The process of the present invention is useful not only for dewaxing a vegetable oil but also for removing a wax together with a phospholipid, free fatty acid, and water from a crude vegetable oil of the oil removes the waxes.

DEODORIZING SECTION

Deodorization is the final stage of refining to remove free fatty acids, odor and color pigments to produce bland oil with a good shelf life. Deodorization process is a mixture of packed column and tray type deodorization. Highly efficient & specially designed packing along with specially designed tray system gives oil maximum retention time and maximum surface area for evaporation.

Bleached and dewaxed oil enters the deaeration vessel. After heating by PHE, oil is sprayed in the vessel and air along with metal traces is removed, evaporated through the vacuum. Oil after deaeration enters regenerative heater which is under vacuum. Incoming oil is heated and final hot oil is cooled down, maximum heat recovery (80-85) % takes place. Partially heated oil is fed to vacuum heater, where oil is heated by thermal fluid or high-pressure steam to 240-250o C. FFA removal takes place during heating and the oil flows under gravity to distillation column equipped with high efficient structured packing which has a very low-pressure drop. A maximum number of distillation stages take place by the counter current flow of oil & vapors coming from the bottom.

Oil after coming from packing is collected at the bottom and fed to holding vessel equipped with a number of trays; here thermal bleaching and deodorization take place. Here all the bad odor and final traces of free fatty acids are removed. After all the deodorization hot oil has to be cooled first in economizer and then by cooler and PHE to about 45o C and sent for storage. Free fatty acid vapors collected from deodorizer, heater and economizer are taken to scrubbing through central ducting and scrubbed in scrubbing column having structured packing. Scrubbing is so designed that traces of fatty acid carryover in the vacuum system and water are reduced to zero level.

• Advantages of Physical Deodorization Plants:
• Maximum Removal of Odor & Flavor
• Maximum Fatty Acid Removal (15-20) %
• Color Reduction by Thermal Bleaching
• Keeping essential Fatty Acids Intact in the Oil
• Maximizing Quantity of Tocopherol, Oryzanol, and Other Nutrients in the final oil
• Low Steam Consumption
• Low Electricity Consumption
• Easy Maintenance
• Low Oil Losses
• Low Water Consumption
• Highly Efficient Scrubbing of Fatty Acid (95% FFA Concentration)
• Minimal Carry Over of Fatty Acids in Water Pool
• High Heat Recovery through Regeneration.

FRACTIONATION PROCESS

Fractional distillation is the process by which oil refineries separate crude oil into different, more useful hydrocarbon products based on their relative molecular weights in a distillation tower. This is the first step in the processing of crude oil, and it is considered to be the main separation process as it performs the initial rough separation of the different fuels. The different components that are separated during this process are known as fractions. Fractions that are separated include gasoline, diesel, kerosene, and bitumen. Fractional distillation allows a lot of useful products to be made from crude oil, with many environmental consequences for the use of those useful products.