Abstract:
In this work, the fluid hydrodynamics of coal and biomass combusted in the circulated fluidized bed (CFB) system was studied. Coal, palm shell and coconut shell were used in this experiment. For the experiment conditions, the fuel feed rate was controlled at 9 kg./hr. with the primary air feed rate of 330 L/min. at room temperature. The CFB was attached with the steam generator which consists of 3 main parts, the water pre-heat section, the heat section and the steam producing section.
The results show that the fluid hydrodynamics inside the riser is the tubulant fluidize action. Continuous after 20 second from starting state. The highest calorific value was obtained when the ratio of coal and biomass is equivalent to 70:30. With the secondary air feed position of 2.4 meters, the system reaches the highest average temperature inside the riser and stable. The pre - heating section reaches the temperature of 80-85 oC by the combusted flue gas. The system can generate steam and the temperature of 165 oC with the pressure of 2.7 bars when using 100% coal. The system also gathers the steam with the temperature of 145 oC with the pressure of 2.3 bars when using the mixture of coal and palm shell and 136 oC steam with 2.2 bars when using the mixture of coal and coconut shell. The efficiencies of the pre-heat section flow rate of 80 L/hr. are 24.96, 22.31 and 13.01. When using pure coal, mixture of coal and palm shell and mixture of coal and coconut shell respectively.