Combustion of CWM (Coal-Water Mixture) and heat transfer characteristics have been studied in a two-dimensional fluidized bed combustor (0.1m$\star$0.2m$\star$0.4m) having an expanded freeboard (0.2m$\star$0.4m$\star$0.5m).
The effects of bed temperature ($700-900\,^\circ\!C$) and gas velocity (0.063-0.092m/sec) on combustion efficiency, entrainment rate and heat transfer coefficients of horizontal and vertical heat transfer tubes have been determined.
The ignition temperature and activation energy of CWM combustion have been measured in a TGA system to be $500\,^\circ\!C$ and 19.5 kcal/mol respectively. The entrainment rate of fly ash increases with inc reasing excess air ratio, but it decreases with increasing bed temperature.
The overall combustion efficiency of CWM droplet increases with increasing bed temperature and gas velocity at high bed temperature (above $800\,^\circ\!C$), but it decreases with increasing gas velocity at low bed temperature (below $750\,^\circ\!C$).
The heat transfer coefficients of horizontal and vertical heat transfer tubes both increases with an increase in bed temperature.
The heat transfer coefficient of horizontal heat transfer tube is higher than that of vertical heat transfer tube at lower gas velocities, but reverse trend has been found at higher gas velocities.
