8. FUEL COMPARTMENT WITH CONDENSATES TRAP
The only tar containing effluent from the whole gas producer
system is the wood fuel condensates formed in the fuel
compartment, when the free water in the wood fuel is driven
off during drying and carbonisation and condensed against
the outside single wall of the fuel compartment.
With the SJG method the resulting fuel compartment
condensates are drained off and prevented from running down
into the hearth and wetting the char, so starting is always
easily done on dry fuel. The condensates are produced in the
small average quantities of between 0,025 litre to 0,05
litre per kg air-dry eucalyptus wood block fuel.
Since the quantity of condensates produced depends on the
moisture content of the wood and during the rainy season
also to a small degree on the moisture content in the
primary air, variations from these limits may occur. When
high density sawdust briquettes or very dry eucalyptus wood
is used, no condensate is produced.
The tar content of the fuel compartment condensates has also
been determined by the environmental water analysts “ERGOSAF”,
who have reported only about 2,5 g tar per litre
condensates, when eucalyptus hard wood fuel was used. ESKOM
tests of the condensates for phenols have established that
the condensates contained between 12,5 mg to 14,7 mg phenols
per litre. However, since the small volumes of condensates
produced do contain phenols, this liquid must not be let out
directly over the ground even if the phenols only represent
less than 1 part phenols in 60,000 parts condensates.
The Inventor has also developed simple methods for the easy,
affordable and safe recycling of the condensates. This is
described in detail in his paper titled “WOOD GAS PRODUCER
FUEL COMPARTMENT CONDENSATES”.
Since the quantities of the wood fuel compartment
condensates produced are small, the solid residues are
easiest and safest finally destroyed in the hearth, after
the odourless water evaporation has first taken place. The
water is either evaporated in sun evaporators used in warm
climates, or in exhaust gas or raw-gas hot evaporators used
in cold or rainy climates.
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