Pre-treatment
The plant has packing based inline mixer and dry degumming vessel for crude oil. In this process Crude Oil is
mixed with mineral / organic acid and given residence time for brief period to coagulate Phospetides /
Proteins/ Metal like Iron. The process will have online integration with next processing system so that it can
be operated continuously as well as limited intermediate storage facility.

Transesterification The catalyst is typically sodium hydroxide (caustic soda). It is dissolved in the alcohol using a standard agitator or mixer reaction. The alcohol/catalyst mix is then charged into a closed reaction vessel and the oil or fat is added. The system from here on is totally closed to the atmosphere to prevent the loss of alcohol. The
reaction mix is kept just above the boiling point of the alcohol (around 160 °F) to speed up the reaction and
the reaction takes place. Recommended reaction time varies from 1 to 8 hours; Excess alcohol is normally
used to ensure total conversion of the fat or oil to its esters. Care must be taken to monitor the amount of
water and free fatty acids in the incoming oil or fat. If the free fatty acid level or water level is too high it may
cause problems with soap formation and the separation of the glycerin by-product downstream.

Separation
Once the reaction is complete, two major products exist: glycerin and biodiesel (methyl ester). Each has a
substantial amount of the excess methanol that was used in the reaction. The reacted mixture is sometimes
neutralized at this step if needed. The glycerin phase is much denser than biodiesel phase and the two can be
gravity separated with glycerin simply drawn off the bottom of the settling vessel. In some cases, a centrifuge
is used to separate the two materials faster.

Alcohol Removal
Once the glycerin and biodiesel phases have been separated, the excess alcohol in each phase is removed
with a by distillation. In others systems, the alcohol is removed and the mixture neutralized before the
glycerin and esters have been separated. In either case, the alcohol is recovered using distillation equipment
and is re-used. Care must be taken to ensure no water accumulates in the recovered alcohol stream.

Glycerin Neutralization
The glycerin by-product contains unused catalyst and soaps that are neutralized with an acid and sent to
storage as crude glycerin. In some cases the salt formed during this phase is recovered for use as fertilizer. In
most cases the salt is left in the glycerin. Water and alcohol are removed to produce 80-88% pure glycerin
that is ready to be sold as crude glycerin. In more sophisticated operations, the glycerin is distilled to 99% or
higher purity and sold into the cosmetic and pharmaceutical markets.

Methyl Ester Wash
Once separated from the glycerin, the biodiesel is sometimes purified by washing gently with warm water to
remove residual catalyst or soaps, dried, and sent to storage. In some processes this step is unnecessary. This
is normally the end of the production process resulting in a clear amber-yellow liquid with a viscosity similar
to petro diesel. In some systems the biodiesel is distilled in an additional step to remove small amounts of
color bodies to produce a colorless biodiesel.

Product Quality
Prior to use as a commercial fuel, the finished biodiesel must be analyzed using sophisticated analytical
equipment to ensure it meets any required specifications. The most important aspects of biodiesel
production to ensure trouble free operation in diesel engines are: