The 90 litre system looks like this:
This system is built around a 105 litre GE hot water
tank. It uses all the same ideas found on the 30 litre prototype system
I developed in 2005. This system is scaled up in size to be more
practical to the fuel needs of the average home or farm
biofueler. A larger recirculation pump and plumbing to suit the
larger tank are the other obvious differences.
The tank comes standard with two heating element ports, but with just a
blank plug in the upper port location. This is conveniently used
to install a float switch which acts as an interlock for the heating
element eliminating the potenial hazard of energizing the heating
element with an empty tank or worse, a tank containing methanol
vapours. As with the prototype it is a vacuum system which allows
for rapid dewatering of feedstocks, and methanol recovery both from the
fuel prior to washing, and from collected glycerin cocktail. A glass
bottle is again used as a liquid trap for the purpose of collecting
this liquid and preventing it from getting into the vacuum pump.
Implosion protection is again afforded by the recycled plastic pail
which also acts as an exhaust shroud and secondary containment vessel
in the unlikely event that the glass bottle should break. Should
this occur the liquid is safely contained in the pail which is
vented outdoors with active exhaust. The methoxide mixing setup is
identical. Since the tank is roughly three times the volume of the
prototype and therefore requires three times the amount of methoxide,
in this case it is mixed in three batches which are added sequentially.
This is better from both a safety and process perspective since it
means that less chemicals are handled at a given time and there is less
overall exposure to humidity during the weighing and handling of the
catalyst. Moisture adsorbed by the catalyst and methanol is a major
contributor to failed processes so mixing methoxide in smaller batches
is better from a process perspective. The mixing unit again uses
recycled materials as much as possible and is exhausted to the outdoors
for safety. The same approach to the frame was used with the sliding
spring loaded (bungee cord seen on the lower right of the photo below)
support for the liquid trap which makes access and changing the bottle
very convenient.
The photo below shows some of the wiring details for the system
including the heater interlock relay. Switched outlets were chosen for
convenience and so that the various electrical components can be
easily removed or replaced.
Here is a shot of a couple of 90 litre systems nearing
completion. Thanks to Ken Riznyk for the pics on this page.
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