Combustion
In a generator that uses wood chips as the fuel a mechanism to move the hearth is
needed. This can be constructed using a car windshield wiper motor. The motor can be
controlled either by hand or automatically. The movement must not be continuous but the
hearth must be moved now and then depending on the size of the wood chips. The
movement removes ash and fine charcoal dust from the hearth and so the suction
resistance is kept within acceptable limits. The motor can be mounted to a suitable place
and connected to the hearth with levers.
- Combustion chamber
- The combustion
chamber consists of a
cylinder with a
diameter of 500 mm
and an air channel
around it. The air
channel is connected
to the air channel of
the outer mantle with
a flange with diameter
of 100 mm. From the
air channel the air
goes to the eight air
nozzles placed evenly
on the periphery of
the combustion
chamber. One of the
nozzles must be
aligned with the air
channel (2) on the
outer mantle to make
it possible for the
starting flame to
directly touch the fuel
in the combustion
chamber thus making
starting of the
generator easier and
quicker. The air
nozzles are
thread-mounted to be
easily replaced if
damaged or need to
be replaced with
differently sized ones.
A bracket is welded
below the air nozzles. On this bracket are mounted adjustment rings, bracket for the
combustion chamber ring and the combustion chamber ring. The adjustment rings
and the combustion chamber ring are separate parts to be easily replaced if the
generator needs to be converted to use different kind of fuel or it is connected to an
ICE with a different cylinder displacement. The round shaped hearth is mounted
inside the lower part of the combustion chamber with four (part 4) brackets. Every
other ring of the hearth is connected to the shaft (2) to be rotated slightly back and
forth. This movement makes the charcoal layer move up and down that makes the
fine ash and charcoal dust drop down through the hearth while the charcoal stays on
the hearth.
-
- Hearth
- The hearth can be made of 5 x 30 mm flat steel. The flat steel is bent to form rings
which fit evenly inside each other. The rings are supported in the middle (2) and
another shaft (3) is welded to the movable rings so that every other ring is movable
and others are stationary. The gap between the rings is selected based on the type of
the fuel, a typical value is 5 mm. The hearth is connected to the other parts with the
flange in the upper end. In the final assembly the hearth is inside the lower part of
the outer mantle. The flange joints are sealed with asbestos gaskets. The dimensions
of the air nozzles, combustion chamber ring and the distance between the hearth and
the combustion chamber ring is selected to match the properties of the ICE to be
used. The distance between the combustion chamber ring and the air nozzles is
adjusted to the right value with the adjustment rings. For proper operation of the gas
generator the dimensions of the following parts and distances are critical:
- combustion chamber ring
- air nozzles
- hearth
- the distances between all these three parts
- If these are not properly dimensioned the generated gas will contain impurities, for
example tar, or the amount of carbon monoxide produced is small.
Translated by Olli.