Free Fatty Acid reduction:
I have worked with resins for 10 years from various manufacturers. We ran trials in the lab on over 100 different resins to convert the FFA to biodiesel. The only problem with the main stream resins is that they were originally developed for lowering the FFA in feedstock so it could be used in tradition catalyst biodiesel production. With enzymes we have a completely different problem.We have 98% reacted feedstock with about 2% FFA unresponsive . The resin trials took 2 years to find a mixture of resins that would lower the FFA to the required specification. It was no problem to get a 75% reduction in FFA but the last 25% posed a monumental problem. With the help of Purolite we were able develop a resin using a very small amount of methanol to lower us to below the required specification of .24 and at a very low temperature compared to other processes.
We now build jacketed FFA reduction columns to do this. We make them in 10 gallon per minutes units. They are plc controlled. You have the option to lower the methanol to 1% of flow of the biodiesel. Certain flow rates work better than others and this is based solely on the feedstock used.