Technicality of Bio-Diesel Industry

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Technicality Of Bio Diesel Industry

Current Scenario:

  • Biodiesel is methyl or ethyl ester of fatty acid.
  • Made from virgin or used vegetable oils and animal fats, used for frying.
  • Aim is to purify and dispose off Used cooking oil.
  • Edible oils are in short supply in India. Used cooking oils is not available in India.

  • BioDiesel

    Considered as clean fuel. Has almost no sul style="line-height: 2.0;"fur, no aromatics. Has about 10% built – in oxygen, which helps it to burn completely.Higher Cetane number improves the ignition quality even when blended in petroleum diesel.
  • B100 has significant environmental benefits.
  • Viscosity of biodiesel is higher (1.9 to 6.0 centi Stokes) than diesel
  • Blends of up to 20% without any problem.
  • Current diesel Engine are designed for 100% biodiesel use.

    Physical Characteristics:

    Specific Gravity 0.87 to 0.89
    Kinematic viscosity @ 40 C 3.7 to 5.8
    Cetane Number 46 to 70
    Higher heating value (btu/lb) 16,928 to 17,996
    Sul style="line-height: 2.0;"fur, wt% 0.0 to 0.0024
    Cloud point C -11 to 16
    Pour Point C -15 to 13
    Iodine number 60 to 135
    Lower heating value (btu/lb) 15,700 to 16,735

    Raw Material:

    Particul style="line-height: 2.0;"ar Diesel Safflow Sunflower Soya
    Density 0.835 0.9 0.915 0.925
    Calorific Value KJ/Kg 42,636 38,038 37,486 37,528
    Cetane Number >40 37 37 37
    Boiling C >150 349 351 350
    % O weight >0 11.65 11.64 11.61

    Trans-esterification Process

  • TriGlycerides (TGs) are converted to DiGlycerides (DGs) and biodiesel.
  • Then DiGlycerides are converted to MonoGlycerides (MGs) and biodiesel.
  • Finally MonoGlycerides are converted to biodiesel and Glycerene is the byproduct on completion.

  • Catalyst:

    • Sodium Hydroxide (NaOH, Caustic Soda).
    • Or
    • Potassium Hydroxide (KOH, Caustic Potash).
    • These two are hygroscopic.
    • Absorb water from the atmosphere.
    • Usually come in three grades.
    • Flakes and 5mm pearls.
    • Half pearls are 96-97%
    • Small pearls (1-2 mm) are 99% +, but more expensive.
    • Any one can be used

    Qualoty Of Catalyst

    • Basis NaOH quantity of 3.5 grams.
    • Extra added due to Free Fatty Acids (FFA)
    • Excess requirement calcul style="line-height: 2.0;"ated by titration.
    • Excess FFA leads to soap formation.
    • FFA shoul style="line-height: 2.0;"d be as low as possible.
    • Flakes and 5mm pearls.


    • Stoichiometric quantity is usually said to be 12.5% methanol by volume.
    • 125 milliliters of methanol per liter of oil.
    • Excess methanol ranges between 75ml and 125 ml per liter of oil.
    • Excess FFA leads to soap formation.
    • Total amount of methanol of 200-250ml per liter of oil.

    Reclaiming Excess Methanol

    • Methanol boils at 64.7 C.
    • Starts vaporizing well before it reaches boiling point.
    • Methanol does not form an a zeotrope with water.
    • Relatively pure methanol can be recovered.
    • Pure enough to reuse in the next batch.

    Manufacturing Process For BioDiesel

    • 90% reaction is complete in 1hour.
    • Allow mixture to settle after 1 hour.
    • Drain all Glycerin formed.
    • Run reaction for 3 more hours.
    • Reaction is complete..
    • Allow settling of Glycerene and remove in it.
    • Dry wash

    Storage Of BioDiesel

    • 90% reaction is complete in 1hour.
    • It is recommended to store biodiesel in clean, dry and approved tanks.
    • Underground storage is preferred.
    • Can be stored in open with proper insul style="line-height: 2.0;"ation, heating.

    Handling of BioDiesel

    • Fire fighting measures to be followed as per its fire hazard classification.
    • Biodiesel shoul style="line-height: 2.0;"d be handled with gloves as it may cause Mild irritation in soft skin

    Environmental and Health Effects

    • Use of biodiesel in a conventional diesel engine resul style="line-height: 2.0;"t in substantial reduction of Unburned
    • Hydro Carbons.
    • Carbon Monoxide
    • Particul style="line-height: 2.0;"ate matter
    • However, Emissions of nitrogen dioxides are slightly increased.

    Properties Of Biodiesel

    • Specific gravity 0.88 compared to 0.84 for diesel.
    • Has higher cetane number than diesel.
    • Has higher viscosity than diesel.
    • Distillation characteristics are quite different from that of diesel.
    • Flash point of biodiesel is around 160C.
    • Cloud Point, Pour Point and Cold Filter Plugging Point (CFPP) are higher than diesel (Problem in Winter).

    Others Problems

    • Free Glycerin can build up at bottom of storage tank and vehicle fuel tank.
    • High levels of free methanol in biodiesel cause accelerated deterioration of natural rubber seals and gaskets. .
    • Water content shoul style="line-height: 2.0;"d be <500 ppm.
    • Ash can cause filter plugging an or injector deposits.
    • Soluble metallic soap, un-removed catalysts and other solids are possible sources of sul style="line-height: 2.0;"fated ash in BioDiesel.