Fluidized-bed drying of parboiled rice using energy from rice hull fluidized bed combustor

Abstract

In the study on Fluidized-Bed Drying of Parboiled Rice Using Energy from Rice Hull Fluidized-Bed Combustor; the fluidized-bed drying system was combined with the fluidized-bed combustor in order to use rice husk from the milling yield of parboiled paddy as a source of energy in parboiled rice fluidized-bed dryer. From the experiments, rice husk was combusted in a 15 cm column at rice husk feed rate of 2,825 g/hr and air feed rate of 30 Nm3/hr. Hot flue gas from the combustor together with hot air from the air heater of 170 Nm3/hr was used for drying of parboiled paddy in the fluidized-bed dryer of 6 cm width and 60 cm length with the parboiled paddy feed rate of 6.5 kg/hr. The temperature of inlet air to the dryer was set at 120, 130, 140, and 150 °c respectively. The height of bed of parboiled paddy was set at 3, 3.5, 4 and 4.5 cm respectively for each temperature. It was found that heat from the combustor was able to supply approximately about 50-55 % of heat required to dryer. Rice husk from parboiled paddy could generate only 66 X of energy from the combustor. The overall efficiency of drying was 7-11 % for the first stage drying and 2-4% for the second stage drying. The major heat, about 90%, was lost with air from the drying column.