Kinetic And Ignition Study Of Fire Combustible Materials

The uncontrolled combustion of solid fuels is destructive in an unwanted fire. Thermal decomposition of solid fuel is the initiation of combustion and greatly related to the consequent ignition and fire growth. Therefore, it is of great importance to investigate the mechanism of pyrolysis and ignition of solid fuel.Most of studies on pyrolysis of different combustibles were firstly presented in this paper, including pyrolysis kinetics, characteristics of pyrolysis and ignition and pyrolysis mathematical model. Based on these studies, both the experimental and theoretical investigation on mechanism of pyrolysis and ignition of solid combustibles were carried out.By using TG analysis, effects of heating rate, the grain diameter of sample and the amount of sample on the process of pyrolysis were studied for some typical wood and engineering timber. It is concluded that the impact of heating rate on pyrolysis of wood is important while the impact of the other two factors could be negligible. The pyrolysis kinetics of different samples was compared under different oxygen concentrations. Then, the pyrolysis of solid fuel in a real fire environment was simulated by using TG analysis and pyrolysis kinetics was analyzed. Based on the previous TGA studies, double components multi-step first order reaction kinetic model was used to describe the process of pyrolysis of wood. By using this model, pyrolysis kinetic parameters of solid combustibles under air and nitrogen atmospheres were calculated.The ignition characteristics of wood were studied experimentally by using the early apparatus designed for testing pyrolysis and ignition of solid combustibles. Some usual woods and engineering timber were tested and ignition time, ignition temperature and mass loss rate were recorded in those experiments.Effects of heat flux, moisture content, orientation, species and external atmosphere on the ignition of solid combustible were investigated experimentally. It could be observed that ignition time and ignition temperature decreased as heat flux increased. Ignition time was obviously delayed as the moisture content increased. The thickness of sample had effect on ignition and ignition time of thermally thin materials was shorter than that of thermally thick materials. Compositions of gas produced from pyrolysis and ignition of different species under different heat fluxes were measured by Rosmont Gas-Analysis Equipment and the relationship among the surface temperature, mass...