Continuous catalytic transesterification of triglycerides in the vegetable oils(rapeseed oil or other) by methanol.

 

• MeONa (Sodium Methanolate) - liquid, easy dosing and manipulation, mild reaction conditions, reactions are  selective to desired products

• Recycling of used MeOH

• Safe and environmental technology

• Capacities of the designed units 10 - 250 kt FAME per year

• Technology according to hi-tech licence

 

Quality of FAME is regulated by standards:

• ASTM D-6571

• international standards

• EU standard EN 14214

 

EN 14214 STANDARD
STANDARD/ Specification	Unit	Limiting Values
		min	max
Ester content	% (w/w)	96.5	-
Density	kg/m3	860	900
Viscosity (40°C)	mm2/s	3.50	5.00
Flash point °C	120	-	181
Sulphur content	mg/kg	-	10.00
Water content	mg/kg	-	500
Free Glycerin	% (w/w)	-	0.02
Phosphor content	mg/kg	-	10.00
Acid number	mg KOH/g	-	0.50
Cetane number	-	51.00	-
Iodine number	-	-	120

 

The transesterification reaction is accomplished in continuous, using three reactors in series operating under mild conditions (i.e.: Temperature = 55°C and Atmospheric Pressure).

 

The transesterification reaction can be represented as follows:

 

Reaction heat is negligible, and a heat supply from outside is necessary in order to keep the reaction mixture at the required temperature. Raw material is continuously fed to the three reaction steps consisting of pump, reaction vessel and relevant piping. The appropriate amount of methanol and catalyst are continuously dosed.

 

Methanol is fed to the reaction unit in a proper excess with respect to the stoichiometric amount with the aim to maximize the transesterification yield and to limit as much as possible the side reaction of saponification. 
Separated obtained glycerine, relatively rich in soap, is directly sent to the glycerine treatment unit. 
Light phase outgoing from the head of the reactor is transferred to the second reaction loop, after the addition of methanol and catalyst. 
Working conditions and the reaction volume of the second reactor are identical to the first reactor. 
Light phase coming from the top of the second reactor is transferred to the third reactor, previous addition of methanol and catalyst. 
Reaction mixture leaving from the third reactor containing the product (Methylester), the excess of methanol and the glycerine (reaction by-product) and a limited amount of soaps is sent to the Methylester purification section.

 

Reaction mixture coming from the third reactor and containing the product (Methylester), the excess of methanol and the glycerine (reaction by-product) as well as the limited amount of soaps (formed by side-.reaction of saponification of Methylester, is transferred to the gravity separator after a partial removal of the contained methanol. Glycerine (containing glycerine, part of the excess of methanol and almost the total amount of soaps) is sent to the glycerine treatment unit.

Methylester phase coming from separator contains glycerine traces, soaps and catalyst; these impurities are removed through washing with water added up with citric acid.

Methylester has to be dried to remove the remaining water and methanol.

The product - methylester is transferred to storage through the pump, after being cooled down to 30° - 40°C.

The unit is designed in order to condense all emergency vents from the upstream production unit.

The methanol coming from the upstream process units is fed to the rectification column.

The rectified and condensed methanol is send to the storage tank.

 

The purpose of the treatment is the acidification of the raw glycerine stream, so to neutralize the residual catalyst and to split the soaps formed during transesterification. Subsequently, the fatty acids derived form soap splitting are separated and the pH of the purified glycerine is finally adjusted.

 

This unit is not strictly required by the process if the water content in oil is per required specification.

 

This unit allows the dosing of CFPP (cold filter plugging point) improver and of antioxidant chemical agents.