Touchless Biodiesel Processor
Dale Scroggins's processor is "a 100-liter biodiesel processor made from mostly salvaged materials that almost fills itself, mixes everything, recovers the unused methanol, washes and dries the ester pretty much by flipping a few switches... I first evacuate the tank, then suck in the oil through a filter setup that I'm a little too proud of. I mix the methoxide separately, using a drill press with a paint mixer installed, then suck it into the tank. Then flip the pump switch. Watch through the clear hoses and marvel. Later, flip off the pump switch, check for separation, flip on the vacuum pump (which is connected to a liquid trap which is connected to the condenser which is connected to the tank) and watch the excess methanol collect in the trap. When no more collects, I open the tank to the atmosphere and drain off the glycerine. Then suck in water and begin the wash." (From a message to the Biofuel mailing list, 11 Jan 2001)
My biodiesel processor, out of the closet (sort of).
The enclosure is made of scrap plywood and lumber salvaged from a set of shelves that the termites had found. If the resolution was better, you could see termite damage on the upper left corner. There is additional steel bracing that isn't visible, so no great loss of strength.
The dimensions were more determined by my reluctance to cut the plywood than anything else. By sticking with the original plywood dimensions, I didn't have to cut much of the framing, either. There are few new parts or materials here.
Principal parts: Tank, vacuum/pressure pump, and mixing pump. And lots of valves. The vertical copper tube near the center is a condenser.
The tank was rescued from the trash collector. I spotted it in my neighborhood, lying next to the street. I had been looking for an electric water heater for some time, something in the 30 to 40 gallon range. This one was 30 gallons. It doesn't look like a water heater any more because I had to remove the outer shell and insulation to fix the leak.
The silver object on the shelf to the right of the tank is the vacuum/pressure pump. It was originally a part of an anesthesia unit; it has a sliding vane type pump on both ends of the motor shaft. In the anesthesia unit, one pump was used to pump ether under pressure while the other was used to supply vacuum for collecting, um, fluids.
Below the vacuum pump, the gray object is a 2hp centrifugal pump. I bought it from an acquaintance who had been storing it in his garage until I needed it :o). This one is probably overkill for the application, but all the pump parts are cast iron, so I'm really not worried about crazing plastic impellers. It is mounted vertically and raised somewhat from the level of the bottom of the tank to eliminate the chance that glycerin might congeal in it. In practice, the pump only has liquid in it during the mixing. Everything is sucked back into the tank immediately after mixing.
The tank is pink because of the insulation I used. I couldn't find anything brighter.
Close-up of the Vacuum Pump
One especially nice feature is the oil system. Each of the two pumps (one at each end) uses the glass bottle in the foreground as an oil reservoir, and an identical bottle (in the background, with only the top visible here) as an oil trap. If the oil becomes contaminated, changing it is easy.
The pump is capable of about 27" hg. The flow rate is outstanding if the pumps are hooked in parallel or series. Only about 22"-25" is really necessary for methanol recovery. The methanol will begin boiling at 22" and 140F, and will be done at about 25".
The Mixing Pump
The pump is mounted vertically, as noted above, to facilitate draining. The gray objects connected to the pump are insulated hoses. The glass jar in the foreground is the liquid trap I use when boiling water out of the oil. Also in the foreground is the lower part of the condenser and, below that, my smoking pipe. The smoking pipe is not part of the apparatus.
The Liquid Trap
This is a pressure pot used as part of a spray painting system. The small pots aren't really expensive when new, and are quite inexpensive used. I have about four, somehow. This collects the recovered methanol. It can hold 2 1/2 gallons, but larger ones are widely available. They could also be hooked in series, as necessary.
My oil isn't very clean when I get it, so I filter it while loading it into the processor. These housings were made of PVC plumbing pipe and fittings. Inside each is a felt bag. Spares are shown draped over the strapping. While in use, the filter has one hose attached at the bottom, thence to the evacuated tank. Another hose is connected to the top of the filter, thence to the dirty oil. Opening the valve on the tank sucks the oil through the filters.
Here's a sketch of how this all fits together: