the effect of binder pitch quinoline insolubles content - Coke Oven ...

COKE OVEN MANAGERS’ YEAR BOOK
obvious. As mentioned previously, the formation of QI is a result of
thermal cracking and polymerization of the coal volatiles in the
“tunnel head”. Therefore, it follows that an increase in temperature
in the “tunnel head” would increase cracking and polymerization
resulting in an increase in the amount of QI formed. The bulk
density of the coal in the coke oven is inversely related to the size of
the “tunnel head”. Therefore, as the bulk density of the coal in the
coke oven decreases the size of the “tunnel head” increases. As the
size of the “tunnel head” increases, the residence time of the coal
volatiles in the “tunnel head” increases.
Increased residence time results in increased coal volatiles cracking
and polymerization giving an increase in QI formation.
Production of Coal Tar Pitch
Coal tar pitch is produced by distilling coal tar. The distillation can
be performed in either a batch or continuous mode. Modern coal tar
distillation is performed using continuous vacuum distillation, which
reduces the thermal exposure of pitch reducing the chances of
mesophase formation. A schematic of the coal tar distillation
process is given in Figure 8.
Coal tar distillation produces three major distillation products
1) chemical oil,
2) distillate,
3) pitch
. Figure 9 summarizes the yields of these distillation products from
distillation of a typical coal tar.
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