Fremgangsmåde til modernisering af et raffinaderi til konventionelle mineralolier til et bioraffinaderi

摘要

The invention relates to a method for revamping a conventional refinery of mineral oils into a biorefinery, characterized by a production scheme which allows the treatment of raw materials of a biological origin (vegetable oils, animal fats, exhausted cooking oils) for the production of biofuels, prevalently high-quality biodiesel. This method allows the re-use of existing plants, allowing, in particular, the revamping of a refinery containing a system comprising two hydrodesulfurization units, U1 and U2, into a biorefinery containing a production unit of hydrocarbon fractions from mixtures of a biological origin containing fatty acid esters by means of their hydrodeoxygenation and isomerization, wherein each of the hydrodesulfurization units U1 and U2 comprises:
- a hydrodesulfurization reactor, (A1) for the unit U1 and (A2) for the unit U2, wherein said reactor contains a hydrodesulfurization catalyst;
- one or more heat exchangers between the feedstock and effluent of the reactor;
- a heating system of the feedstock upstream of the reactor;
- an acid gas treatment unit downstream of the reactor, containing an absorbent (B) for H 2 S, said unit being called T1 in the unit U1 and T2 in the unit U2,
and wherein said method comprises:
- installing a line L between the units U1 and U2 which connects them in series;
- installing a recycling line of the product for the unit U1 and possibly for the unit U2,
- substituting the hydrodesulfurization catalyst in the reactor A1 with a hydrodeoxygenation catalyst;
- substituting the hydrodesulfurization catalyst in the reactor A2 with an isomerization catalyst;
- installing a by-pass line X of the acid gas treatment unit T2 of the unit U2;
- substituting the absorbent (B) in the acid gas treatment unit T1 with a specific absorbent for CO 2 and H 2 S. The operative configuration obtained with the method, object of the present invention, also leads to a substantial reduction in emissions of pollutants into the atmosphere, with respect to the original operative mode. The invention also relates to the transformation unit of mixtures of a biological origin obtained with said conversion method and particularly hydrodeoxygenation and isomerization processes.