[Bioconversion] Veg Lister

[Ken Boak]

Rex & list,

The conversion of the Lister to running on waste vegetable oil can be very
simple, depending on the ambient temperature, an oil pre-heater coil is all
that is needed.  Some enthusiasts also fit an automotive diesel glowplug
into the head of the Lister, to electrically pre-heat the combustion
chamber.

For dual fuel operation,  the flammable gas need only be introduced into the
air intake through a mixing valve.  The induction stroke of the Lister will
draw in roughly equal quantities of air and woodgas. There should be a link
from the engine governor to the gas valve - such that the governor can
control or restrict the quantity of gas, and also allow a positive gas
shut-off.  The details of suitable gasifiers can be found on the woodgas
sites, or a commercially available unit from Ankur Scientific - who's site
gives some good technical background.

http://www.ankurscientific.com/

Some experimentation will be needed to get the optimum gas/air ratio.  As
the gas is introduced, the engine governor will control the position of the
fuel injection pump rack, and therby limit the quantity of veg oil injected
in each stroke.  It should be possible to reduce the veg oil consumption to
about 20%, just enough to provide pilot ignition and overcome the mechanical
losses of the engine. On my engine, this is about 360ml of veg oil per hour.

The benefits of dual fuel, is that the engine can be started and run on veg
oil alone,  and provide mechanical, electrical  and thermal energy for
assisting the gasifier, until it is producing good quality gas.  I hope to
use a spiral  electric stove element to assist the lighting of the gasifier,
and a hot air gun makes an ideal controlable source of pre-heated air for
ignition,  (I have previously lit barbeques using just a 1600W hot air gun).

I believe that the combination of the Lister and a wood chip gasifier, would
make an ideal experimental combined heat and power system for domestic sized
properties.  Wood chips are one of the cheapest fuel available, and if their
calorific content can be efficiently used to produce both heat and power,
then this will help offset the use of domestic fossil fuels and lower the
carbon footprint of the domestic energy used.


Ken