Thermo-physical and kinetics parameters determination and gases emissions of self-ignition of sieved rice husk of different sizes on a hot plate

Hot plate self-ignition standard tests at constant temperature have been performed on a paddle rice husk of size 75 to 1500 mu m and a sieved rice husk of sizes 75 : 106, 106 : 120, and 120 : 150 mu m. Modified tests using insulated metal ring have been investigated and compared with the standard test. Gases emissions showed that CO is the main component, and its maximum percentage occurs at the maximum temperature and depends on the dust layer thickness. It was found that as the thickness of dust layer increases, the maximum temperature and its corresponding time increase. Ring with insulation showed lower maximum and ignition temperature and ignition time compared with that without insulation. The flue gases temperature and CO% and CO2% emissions were higher in case of insulated ring. Thermal and physical properties as density, thermal conductivity, heat transfer coefficient, and kinetic parameters as activation energy and frequency factor have been determined. The activation energy of the sieved husk (75 : 106, 106 : 120, 120 : 150 mu m) and paddle husk was 174.76, 183.37, 189.1, and 206.1 kJ/mol, respectively. Also, (QA(0)) factors were 2.696 x 10(14), 6.211 x 10(16), 6.105 x 10(19) and 3.0461 x 10(16) (J/kg s), respectively. It has been noted that as the dust particle size increases, the (E) and (QA(0)) values increase. (C) 2017 Curtin University of Technology and John Wiley & Sons, Ltd.