If we look initially at the raw feed stock used in the production of Biodiesel we find that the majority of pre filtration can be as simple as Bag Filters used as a roughing filter to remove coarse solids. An ideal first stage is to use Nylon Monofilament bags as these items, if treated carefully can be washed and re-used. These same products, but in a much finer micron retention can be used as either a first stage in the final polishing process or in conjunction with anhydrous powders such as magnesium silicate. We now offer the ability to temporarily modify our polypropylene housings to allow them to be used as a resin chamber for use with the newer polymer beads.
Depending upon your final flow rate criteria, a low cost polypropylene spun bonded depth cartridge is ideal for fine solids removal to help meet the requirements of EN14214 or EN590. We have an ideal balance between efficiency (90% at stated micron ratings) and cost, with our Avasan element. For larger flow rates, we can offer multi-cartridge vessels in 316L stainless steel or make use of existing Hydrocarbon vessels with the FBO or RVFS depending upon your budget.
Finally water removal. Due to the inherent characteristics of Biodiesel, the surface tension is very low, and this readily allows water to remain entrapped. Depending on the size of operation, and the volumes of water to be removed, there are several bulk water removal methods none of which lend itself to industry standard coalescers. Ideally the use of a centrifuge or vacuum dehydration as a first stage for high water content removal would be beneficial. At this point, we are able to use proven technology to reduce the water levels even further. As mentioned previously, due to the very low surface tension we need to oversize the unit significantly, normally at least by a factor of eight to allow for mechanical coalescence to occur.