BioDiesel

Pre-treatment section:

The Pre-treatment consisted of degumming and/or an bleaching, which Together remove certain non- volatile impurities by filtration. Feed stocks containing Phospholipids/gums goes under Degumming process where phosphoric acid mixes with Oil and formation of gums takes place. These gums separated in centrifuge In the bleaching process, bleaching earth is applied to crude oil, minimizing its content of pigment (e.g., carotenes and chlorophylls), heavy metals, and the phosphorus Remaining after degumming. This improves the appearance of the oil. Bleaching is based on the principle of adsorption of unwanted substances onto bleaching earth. Reaction in the bleacher through the heat exchanger. Bleaching earth is dosed into the bleacher and mixed intensively for a determined time period under vacuum. After bleaching, the oil is pumped into a filter, where bleaching earth is retained and subsequently dried. The filter then releases bleached oil and earth falls out at specific intervals. Pre-treatment is carried out depending on type of feed stock. PFAD, PALM STERIN and TALLOW FAT does not require pre-treatment.

Esterification and Trans-esterification section

(Fat Modification) Enzymatic process catalyses’ both esterification and trans esterification reaction. Trans esterification is the process where glycerides present in the oil are converted to methyl eater while esterification is the process where free fatty acids in the oil get converted To their methyl esters in presence of enzyme and methanol. Oil is taken into the agitated reactor where desired oil temperature s to be maintained. Diluted caustic lye (10%w/w) solution is added in the reactor to maintain the ph between 5.5 to 6. Water (2%) is added in the reactor to maintain the moisture content required for the activation of enzyme. Enzyme 0.25% to 0.3% is added in the reactor. Typically, 20% methanol based on initial oil content is required for the reaction. Desired flow of methanol over the 24 hrs is maintained.

Flashing section

flashing is the process where methanol and water from crude bio diesel is removed. Crude bio diesel from esterification reactor is transferred to tank. Mixture is heated and fed to the flash tank. Methanol & water vapor from flash tank is condensed in the flash tank vapor condenser. Methanol water condensate is collected into the methanol recovery column feed tank which is fed to the methanol column. Bio diesel and glycerine phase which is free of methanol is centrifugation section.

Glycerine separation section

This process separates glycerine from crude bio diesel. Contents from feed tank is fed to the decanter. Based on the density difference decanter separates crude biodiesel (FAME) and crude Glycerine. crude glycerin is fed into centrifuge for further purification. Crude biodiesel from decanter and centrifuge is collected in the tank. Crude biodiesel is transferred to neutralization section.

1. a) Neutralization-Washing-Drying Section

   Purpose of this step is to remove unreacted free fatty acids from crude biodiesel (FAME). FAME is heated up to 80 – 85 degc and stoichiometric amount of 10 % NaOH solution plus 10 % extra is added to the crude biodiesel phase. Neutralization is carried out for certain residence time. After the reaction, the mixture is fed into centrifuge to separate soap stock and neutralized Biodiesel. Soap stock then transferred to storage tank. FAME is fed to washing centrifuge to remove residual soap The residual soap up to 600 ppm remained in neutralized FAME is reduced by water washing or citric acid washing. Hot water is mixed with oil and passed through centrifuge. Washed bio diesel is transferred to flashing section Washed biodiesel contains up to 1 % moisture fed to flashing section to remove moisture present in biodiesel, Moisture removal in the flasher occur in conditions of vacuum and temperature. The Biodiesel is pumped to the flasher through the heat exchanger. The vacuum is maintained by vacuum pumps or ejectors that have their own cooling systems and storage tanks for the working liquid (water).  Dried biodiesel further transferred to distillation section.

1. b) Bio Diesel Distillation Section washed FAME fed to molecular distillation column. Distillation is carried out under deep vacuum. Up to boiling point of FAME mixture is heated using thermic fluid heating system. FAME condensed in distillate tank and impurities condensed in residue tank. h) Methanol Recovery Section The Methanol recovery section consists of methanol distillation column , is mainly used for separating water and methanol during biodiesel production in order to recycle and obtain highly purified methanol.