The FFA esterification process can be easily tied-in between the oil pretreatment and the transesterification units of a conventional biodiesel process. The pretreated oil will be directly fed together with dry methanol into the first esterification reactor stage. After the last reaction stage the FFA initially contained in the feedstock will be converted to FAME and the resulting product stream can be further processed in a conventional transesterification unit to convert the triglycerides into FAME as well. The esterification product stream will additionally contain the excess methanol from the last reaction stage, which will not be removed in order to minimize energy consumption and will therefore reduce the methanol requirement of the transesterification unit.

With an installation of the FFA esterification process the severity of the oil pretreatment can be reduced in cases where currently low FFA concentrations are removed as soap stock. The yield loss that is so far caused by the soap stock purge will be converted into the final biodiesel product with the help of the esterification process and thus result in a considerable increase of the overall product yield. In case the existing conventional biodiesel process already comprises a methanol distillation column with spare capacity this offers a potential to reduce the investment for the esterification process by implementing an integrated methanol recycle for the entire biodiesel unit. The esterification process will need similar feedstock purities like a conventional transesterification processes, which are usually achieved by a state-of-the-art biodiesel pretreatment unit (degumming and /or bleaching). However, to sustain a high lifetime of the esterification catalyst the reactors should be protected from impurities such as ionic species and components that are potential sources of fouling. This will be ensured by an ion exchanger (AMBERSEP™ BD19 resin) guard bed that captures these impurities and therefore protects the active catalyst. For biodiesel plants that do not yet include a feedstock pretreatment unit, Bayer Technology Services can offer support in selecting the most cost effective pretreatment strategy and integrating this into the esterification unit.