One of
the things that the human race has in common appears
to be an insatiable appetite for three things... sugar,
salt, and OIL. The last of these is an interesting
one, particularly because it comes in many forms -
vegetable oil, olive oil... and the list goes on.
The deep
fried junk that we have for lunch and dinner creates
gallons and gallons of dirty used cooking oil at the
back of restaurants which we would rather not see.
But in actual fact this dirty liquid makes an extremely
powerful fuel (aided by burnt potato bits) which just
makes sense in a furnace!
|
Used cooking oil...
a free & environmentally friendly fuel
|
A brand
new crucible - beautiful!
|
Vegetable oil has the potential
to burn very ferociously under the right circumstances.
It was thus decided that the old tin-can crucibles
would be absolutely out-of-the-question. New idea?
An old fire extiguisher!
This poor old extinguisher
was just slowly karking it at the back of a church,
so I decided to empty out the powder and take to it
with an angle grinder. There on the left, we have
ourselves a beautiful new thick-walled crucible.
|
To modify
the furnace to take used vegetable oil, some sort
of feeding mechanism was needed. After a bit of deep
thought, I came up with this mechanism using a few
old scrap pieces of copper tubing and joiners, complete
with a ball valve to control oil flow.
The large
steel tube at the base is an air inlet, once again
for the purposes of providing oxygen to the base of
the furnace. However, as seen in the next slide, it'll
also have a much-needed second function.
|
Oil feeder tube
|
Schematic of oil feeding
physics
|
When the oil tank (not
pictured) is mounted above the feeder tube, the oil
is brought down to the ball valve by the force of
gravity. If the valve is open, the oil continues to
flow around the bend and into the steel tube. At the
same time, highly compressed air is blown into the
steel tube, hopefully atomizing the oil particles
and resulting in a fine mist of oil at the output.
This fine vegetable oil
mist (sounds delightful...) turns out to be remarkably
flammable and serves as an ideal furnace fuel.
|
In order
to increase the pressure of the air right at the point
where the oil arrives in the steel tube, a steel nozzle
(pictured) was fashioned out of sheet metal and shaped
into a cone.
This cone
fits snugly inside the steel tube and directs a jet
of air right into the oil outlet.
|
Steel nozzle for pressurizing
air
|
The new furnace setup
|
Putting all the parts together,
we have here the completely trial setup for this brand-spanking
new feeder tube.
On the top of the ladder
there is the oil tank (inverted orange juice carton)
whose tube connects to the feeder mechanism. The old
furnace is back, with the original air inlet replaced
with the steel air tube. At the inlet of the steel
tube, I've used the output of a vaccuum cleaner (not
pictured) to provide the pressurized air.
|
It took
quite a while for everything to set into place and
function as designed. For instance, the ball valve
had to be moved very delicately. If it was too open,
too much oil would flow and the ignition source (I
used some cardboard and BBQ bricks) would be drenched
and put out.
Upon first
light, however, the furnace burned magnificently...
|
First light! The oil
burning furiously away!
|
An over-excited furnace
gobbling up some oil
|
One of the most interesting
things one notices from using a used vegetable oil
furnace is the smell which eminates immediately from
the fire. A subtle blend of KFC chicken nuggets, spring
rolls, potato chips and McBurgers with a whiff of
burnt pig fat. Yuck. I bet you get fat just inhaling
this stuff.
Of the many things that
could be improved with this setup, one of the more
concerning was the proximity of the plastic oil hose
to the fire itself. Hmm...
|
Here
the furnace is cooling off after an intense session!
This little guy has survived many things and has many
stories to tell.
Notice
all the burnt bits of god-knows-what strewn about
on the bricks. Just absolute chaos. Interesting to
also note that the grass around this area was dead
the next day. Now are you concerned about what goes
in your McDonalds deluxe burger?
|
A scorched earth
|
