Converter consists of two chambers, an inner
pyrolysis chamber (PC) and an outer heating chamber.
The outer heating chamber totally encloses the
inner PC and acts as a heating
The outer heating chamber is designed to increase
the temperature of the inner PC to 850°C,
it is heated initially by burning propane gas
in the secondary converter (SC) . When the PC
reaches temperature, and pyrolysis begins,
some of the generated gas is then diverted to
the SC and the propane
is shut off.
The pyrolysis process requires
an oxygen free atmosphere, hence an inert gas
is introduced into the PC to replace the
atmospheric gas, and nitrogen is used for this
purpose. The nitrogen gas is fed into the unit
by a network of pipes from an external storage
vessel; the nitrogen is turned off once an oxygen
free atmosphere is achieved.
The dry feed is then transferred,
by mobile plant fitted with a front scoop, on
to a conveyor, which transports the feed to a
metering bin that feeds into a hydraulic compaction
system that compacts to a solid state used to
stop any atmospheric air entering the PC by squeezing
it out of the waste.
A ram feeder, at one end of
the PC, governs the rate of introduction
of the dry feed into the PC
from the compaction system. The feed is rapidly
dissipated in the PC.
Due to the high temperature and the lack of oxygen the organic compounds are broken into short chain length organic compounds, which would be gaseous at room temperature, hence up to 99% by weight of the feed will vaporise to a gas. This process is known as thermal cracking.
This gas generated will then be passed through a filter to remove any remaining particulate material.
All non-converted elements (char)
will be collected as carbon ash at the far end
of the PC. There are rotary valves, which will
allow the removal of the char without losing
the inert atmosphere. This char (assumed to be
rich in carbon) is quenched before being transferred
to the SC stage where any remaining
energy is utilised, leaving a vitrified slag
to be used as building material.