Biodiesel


The biodiesel is a renewable source of energy derived from vegetable oil. In Romania as well as the rest of the EU, the legislation stipulates that the petroleum companies introduce a mandatory quota of biodiesel, currently at 4% with a targeted level of 5.75% by the year 2010.

Biofuels have a dual role to play in the transportation industry. They are currently the only direct substitute for fossile oil in transport that is available on a significant scale, and which can be used today, in ordinary vehicle engines (unmodified for low blends, or with cheap modifications to accept high blends).

It should also be taken into consideration that diesel is the predominant fuel used in Europe. Another important advantage of using biofuels is their impact on reducing greenhouse emission.

Moreover, biodiesel produced from rapeseed helps the EU to increase its production of meal to feed cattle. Its imports of soy meal hence decrease thanks to biodiesel production. With each litre of biodiesel produced from rapeseed, comes about 1,5 kg of meal that feed cows, pigs or hens, which feed human.

Facilities

Expur has built a brand new 100,000 ton biodiesel facility which is supplied by internally produced oil and whose production is sold mainly on the local market.

Process

The plant is designed for the production of methylesters starting from a vegetal oils mixture feed, by means of a reaction between try-glicerides and methanol, in presence of an alkaline catalyst. Glycerine is obtained as a by-product and separates from the product.

The unreacted methanol splits between the methylester and the glycerine phases. As both side reactions occur in presence of moisture, guaranteeing a reaction system that is as dry as possible is essential. For this, the oil stream is subject to a flash drying before being fed to the transesterification unit and the excess methanol is subject to rectification before being recycled to the transesterification.

The methylester stream coming from the transesterification unit is subject to a purification process in order to remove the excess methanol, moisture, and the impurities. The glycerine stream separated from the transesterification unit undergoes a purification process as well, in order to remove the dissolved methanol and the impurities incorporated during the transesterification reaction.

In order to maximize the overall methylester yield, fatty acids coming from the glycerine purification step are subject to an acid-catalyzed esterification step, which allows converting them to methylester by direct esterification with methanol; high-acidity used frying oils can also be mixed with the fatty acids and fed to the esterification unit.