In order to enhance the overall thermal efficiency in blast furnace system
as well as coal gasifiers, it is necessary to elucidate fundamental reactio
n characteristics of pulverized coal at high temperature. The experiments w
ere carried out using a horizontal pulverized coal reactor with a pre-combu
stor to produce vitiated air at high temperature and high-oxygen concentrat
ion. The reaction behavior of coal during combustion and/or gasification ar
e elucidated by means of sampling and analyzing both reacting particles and
reaction gases as well as optical measurement of the instantaneous particl
e temperature. Evolution rate of the volatile matter for various types of c
oal at high temperature is obtained from the Arrhenius plots.
As a result, the volatile matter is rapidly evolved as soon as coal particl
es are introduced into the furnace since temperature of the vitiated air in
creases sufficiently. Result shows that the evolution rate of volatile matt
er does not depend on coal types. Activation energy and frequency factor of
the evolution rate of volatile matter for various types of coal remain alm
ost constant in the particle temperature range of 2200 to 2700 K, even when
other experimental conditions were varied. In the char combustion region,
char structure was found to affect the reaction rate of fixed carbon. It is
observed that coal, which forms a network-type of char, indicated reaction
rate of fixed carbon which did not always increase even when the vitiated
air temperature was high enough. For a balloon-type char, on the other hand
, the reaction rate of fixed carbon decreased with an increase of the vitia
ted air temperature.