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An Appleseed Biodiesel Processor in action in Cocoa, FL
Write-up and photos by Jay Wherley
I recently had a chance to visit a local NASA engineer who is making his own biodiesel fuel using a version very similar to the one used by Graydon of UtahBiodiesel.org and based on the popular open-source Appleseed processor. The processor has a used water heater (someone else's trash from the side of the road) which performs a "transesterification" conversion on waste vegetable oil. The 55 gallon tank on the left is used as a wash tank. During washing water is misted and/or bubbled thru the biodiesel to carry off any soap/impurities from the processed biodiesel. I noted that many of his components came from B100 Supply LLC which Elias was very happy with.
The first step in using the waste oil is filtering. Elias performs two steps of filtering. The first uses a large 200 micron sized filter to block all the big bits of crud. This improved version of the oil is then passed thru a 5 micron filter after which it is ready to be used in the processor.
To prepare for the conversion process, Elias carefully titrates the waste oil. His worksheet shows that he performs many titrations to ensure that he has a good stable reading. The result of the titration determines the amount of catalyst necessary for the reaction. Elias uses sodium hydroxide (NaOH) which he obtains in the form of common drain cleaner ("Lye") from a local hardware store. The sodium hydroxide is added to methanol, which he obtains through some racing fuel supply connections, to produce methoxide. His first 100 litre batch used a 3.5 gram / litre starting amount of NaOH, but he has now gone to a 5.0 gram / litre starting amount. The titration result determines the addtional amount of NaOH required for the particular waste oil being used. The NaOH will neutralize the Free Fatty Acids (FFA) in the oil. The amount of waste oil processed at one time is 100 litres in this setup. On that first batch Elias also used 20% (20 litres) of methanol as input. On this batch he increased that to 22% (22 litres) to help ensure a more complete reaction. The methoxide mixture was prepared a day or two in advance of the conversion process. Elias stores it in these carboys containing 11 litres each:
On conversion day, the first step is to get the waste oil into the hot water heater tank. (At this point the tank is unplugged.) Elias uses a hand pump to do this. The plumbing controls are used to direct the oil into the tank during this step.
Next, the control valves are set to provide a circulating path thru the external pump . This pump, and the lower hot water heater element are powered via a generator (diesel running on biodiesel of course!). The hot water heater is turned on and the pump is activated to begin heating the waste oil. The goal is to bring the oil up to a temperature of 130F. The temperature is monitored via a gauge which attaches to the plumbing fixtures.
It took about 2 hours to get the oil up to temperature. Near the end of that time the temperature was going up at about a degree F per minute or two. Elias did need to make a tweak to the thermostat setting in the hot water heater to get that final temperature adjusted.
Here one of the prepared methoxide containers is about to be connected into the processor. It is placed on the high shelf and its contents allowed to slowly mix into the circulation process via one of the plumbing control valves. During this time the heater is off, but the pump is still running. The oil does start to cool down a little bit during this process, down to about 120F or 110F by the time all 22 litres were added.
The circulation process was run for about 2 hours after the methoxide was added. Elias then allows the tank to sit for two days or so to try and get a good separation of the biodiesel from the glycerine waste product which will form in a lower layer in the tank. This remains liquid and can be drained off first from the spigot at the bottom of the tank. The biodiesel itself is then pumped into the 55 gallon wash tank. This tank has a bubbling ring of water tubing at the bottom, and a misting ring of water jets at the top. First, a few rounds of mist washing are performed that spray a fine mist of water on top of the biodiesel. This water settles down to the botton of the wash tank carrying soaps/impurities with it. There are two drains on the 55 gallon tank, one each connected to the original fittings on the barrel (now upside down). The lower drain can be used to draw off the settled waste water. A standpipe drain can be used to draw off biodiesel, as long as no more than 7 inches or so of water have settled to the bottom of the tank. After a few rounds of mist washing and then bubble washing the biodiesel is almost ready. Elias also likes to "dry" his fuel. This is the process by which any remaining water is evaporated out of the biodiesel. Elias has found that getting the fuel into sunlight in large surface area drawers helps with this process. At the end of these steps Elias has between 20 and 25 gallons of biodiesel which can be used in any diesel engine.
On the day these pictures were taken, 2 gallons from a previous batch of biodiesel were used to power the generator which ran the heater and pump. Another 5 gallons were poured into a Ford Powerstroke pickup used by Elias's co-worker Ed.