Computational Fluid Dynamic (CFD) of Drying Process of Sewage Sludge

The Sewage Sludge (SS) is very high in moisture content in its raw state after mechanical drying process from the water treatment plant. It would be in the best state for power boilers after being dried. SS as solid fuel need to be dried to 30% of its moisture content before fed inside the boiler or incinerator for optimum burning. There is no industrial scale of utilizing SS as solid fuel in Malaysia, thus the experiment conducted is very important in getting the reference parameter. Experimental scale of SS dryer has been fabricated to study the drying process behavior and search for the optimum working parameters. However, as the designed parameters; length, diameter, and dryer rotational speed, are fixed, there are limitation in finding the best working process. Besides, detail behavior of drying process unable to be studied through experiment. In the present paper, the actual experimental design of the dryer is stimulated in Computational Fluid Dynamic software (CFD). Generic design allow to vary the design parameters in finding the optimum working data and detail behavior of drying process such as thermal distribution able to be verified. Accordingly, an experiment was carried out to find the actual heat distribution. Then, the simulation result on the heat distribution to SS is compared with experimental data and has been verified with deviation of 13.5% from the actual. Drying process of current design is not at optimum state and several improvement is necessary on its working parameters. The application of CFD software is practical to be applied for design process of SS dryer in order to have the best working parameters which ensure the best quality of output product.