We have looked at centrifugal dryers. We commented on the Delta unit which is simply beautiful, but with limitations. As per industrial centrifugal dryers (like for laundry and textiles):
- They are huge with large footprint.
- The larger machines spin slower, so the bigger the less solvent you will recover.
- They are expensive, especially the ones made domestically.
- They are manual machines so you would have to take your bags (if you use bags to wash) and dump your biomass into the dryer manually as i’m pretty sure bags would unbalance the machine if you did a spin with bags.
Lots of manual processing here which in a few years will seem silly having so much manual labor in the process.
A press works better for several reason:
- It’s fully automated so there is no touching the plant; one unskilled operator (with training) can handle the whole operation.
- Though there is squeezing of the biomass by no means is it like using a hydraulic press or rollers to squeeze the remaining solvent out of the bags. It is far gentler and you can pick the pressure used.
- You can easily wash the biomass with cold ethanol and remove residual compounds that way, so if there is a loss its some solvent not active compounds. Since you wash the biomass that is packed in the press at the end of your cycle, not in your reaction vessel there is less solvent needed to wash.
- When you do squeeze the biomass you are squeezing a pretty cold biomass; when you squeeze in a roller, that biomass is close to room temperature most likely so more green stuff comes out at that point than on a cool press environment. Also, in a press you squeeze all biomass at the same time; when you press bags the first may yield a yellowish filtrate but the last probably will be very green.
- The solvent that does come out the press is simultaneously filtered so there is no debris of any kind to clog up or FFE, etc…
- You can blow air or another gas through your biomass to further dry it, which also cleans your pipes for an absolute recovery.
These press systems can get massive. Correct me if i’m wrong but a cubic foot of trim is about 10 pounds, when compressed it may be more. I got a small system that is for 50+ pounds and we can easily do systems of multi ton units. Obviously the bigger the system the cheaper cost per pound. Solvent and labor savings make the ROI on these things huge.