Method and system for producing biodiesel

A process for producing biodiesel from fats, oils or split fatty acids containing steryl glycosides, wherein the fats, oils or split fatty acids are reacted with short-chain alkanols in the presence of a catalyst by transesterification or esterification to a fatty acid alkyl ester so as to obtain a first product stream rich in the fatty acid alkyl ester as a first light phase of a first liquid-liquid phase separation, the process comprising:

• a) washing the first product stream with water in a washing device so as to form a suspension layer on a phase boundary layer between a heavy phase rich in water and the first light phase rich in the fatty acid alkyl ester;
• b) treating the suspension layer including the steryl glycosides, the fatty acid alkyl ester and water by introducing kinetic energy;
• c) withdrawing a second product stream from the first light phase as a second light phase which contains the steryl glycosides in at least one of a homogeneously dissolved form, a colloidally dissolved form and a finely dispersed form of steryl glycoside/fatty acid alkyl ester/water agglomerates;
• d) intensively mixing the second product stream with water so as to obtain a third product stream as a third light phase of a second liquid-liquid phase separation, the third product stream including steryl glycoside/fatty acid alkyl ester/water agglomerates which are separable from the third product stream by a mechanical separation;
• e) performing the mechanical separation of the third product stream so as to provide a fourth product stream and a fifth product stream;
• f) withdrawing the fourth product stream from the mechanical separation as a fourth light phase;
• g) withdrawing the fifth product stream from the mechanical separation as a heavy phase enriched in steryl glycosides;
• and
• h) performing a product conditioning on the fourth product stream so as to obtain on-spec biodiesel.

A plant for producing biodiesel from fats, oils or split fatty acids containing steryl glycosides, the plant comprising:

• at least one reaction stage configured to react the fats, oils, or split fatty acids with short-chain alkanols in the presence of a catalyst by at least one of transesterification and esterification so as to obtain a first product stream as a first light phase of a first liquid-liquid phase separation, the first product stream being rich in the fatty acid alkyl ester;
• a washing column configured to receive the first product stream from the at least one reaction stage via a first conduit and wash the first product stream with water so as to obtain a second product stream as a second light phase;
• at least one mixer configured to receive the second product stream from the washing column via a second conduit and intensively mix the second product stream with water so as to obtain a third product stream as a third light phase of a second liquid-liquid phase separation;
• a mechanical separating device configured to receive the third product stream from the at least one mixer via a third conduit and separate the third product stream into a fourth product stream as a fourth light phase of a phase separation and a fifth product stream as a heavy phase enriched in the steryl glycosides;
• a fourth conduit configured to supply the fourth product stream from the mechanical separating device to a product conditioning device so as to obtain on-spec biodiesel;
• and
• a fifth conduit configured to withdraw the fifth product stream from the mechanical separating device and supply the fifth product stream to at least one of a disposal area and an additional processing station.