3.4. Energy consumption of lignite drying
The lignite is predicated on its growing utilization as fuel. Therefore,
it is necessary to develop a low energy consumption drying system. An
acoustic fluidized bed dryer is used as the evaporatorwith the consideration
of its good performance on rapid transfer of heat and mass,
uniform temperature distribution, etc. Specific unit energy consumption
(Es) is defined as the energy required for evaporating water from
lignite (MJ/kg) during drying
Es ¼ Pt3:6
.
mW60
ð4Þ
wheremW is themass ofwater evaporated (kg), P is the input electrical
power (kW), and t is the total drying time (min). The estimated Es
values were found to depend on the power supplied by the oven
(1.8 kW) and sound system (0.25 kW), initial moisture of lignite and
the drying time. Therefore, the input power and drying time play an
important role in energy consumption. According to Fig. 9, the drying
time is 7.5 min and 30 min when the moisture content ratio MR value
is 0.1493 in a fluidized bed with and without acoustic excitation,