Research On Pyrolysis And Burning Experiment Of Logs’ Pile

The fire is a burning phenomenon that fuel is out of control in the spread. Pyrolysis is the first step of fire, greatly related to the consequent ignition and firegrowth.and it plays a key role whether the fire can happen and process to the maintenance. Therefore, it is of great importance to investigate characteristics of pyrolysis and burning for logs in log yard.In this paper, the characteristics of different pyrolysis for chips was analyzed and compared in different atmosphere, which was measured by Q600synchronization of TA thermal analysis in the United States. In different atmosphere, the scope of pyrolysis temperature was different. In the air atmosphere, there were two steps in the pyrolysis process and two peaks in the DTG curve. In the nitrogen atmosphere, pyrolysis behaved as a process. The pyrolysis reaction was faster with the increase of the heating rate, and diameter of particles had less effect in the pyrolysis process.The pyrolysis kinetics was used to describe the process of chips by Coats-Redfern Integral method, and the most appropriate kinetic mechanism function was selected by y(α)-α curve. The pyrolysis models were set in the air and nitrogen atmosphere respectively, and pyrolysis kinetic parameters were calculated.Based on principle of oxygen consumption, Flame spread of logs’pile of larch wood was studied in a ISO ROOM full-scale test apparatus. Through varying the experimental ambience, the transformation characteristic of heat release rate and temperature field were researched, and the relation of heat release rate between temperature and O2was analyzed. It was observed that there are many factors influence log fire spreading which included the acreage of the oil basin, exhaust capacity and accumulation quality. Once the combustion of log was to level off, the heat release rate was keeping in a constant. With the increasing of heat release rate, the field of temperature was going up. In the same time, O2was in linear relation with the heat release rate.By a whole scale combustion experiment with wood pile of larch wood sylvestris var. mongolica, we studied the characteristics of temperature field when wood pile burning, and analyzed the effects of sizes of wood pile and wind speed on variation in temperature field. It showed that the temperature in wood pile might reach as high as900℃when it was burning, and temperature is roughly rising linearly around the bottom and central of the pile. Under the condition of equal distance from the facet studied to wood pile, the temperatures varied greatest in the facet perpendicular to the direction of wind flow. Larger size of wood pile and faster wind speed might accelerate the rate of combustion so that it made faster increment in environmental temperature. At same time, it was hidden when the pile was burning, so it was easy to produce back to burning phenomenon. Field simulation was a method through the computer that related to parameters in fire space by time. Based on large eddy simulation combustion model, numerical simulation for the change disciplinarian of temperature field and smoke in the course of logs’ pile combustion was studied by FDS. The correctness of the simulation model was varied by comparing the experimental data and the numerical simulation data.Through the theoretical analysis and experimental research on kinetic and burning of logs’ pile, characteristics of fire was discussed by the macro and micro of timber,and database of burning characteristics and discipline were get. These results could provide information to fire fighting and rescue.