Study On The Combustion Process And Thermokinetics Of Conifer Cones

Conifer is a plant of the order conifer.The leaves are acicular,evergreen and globular.Trees belonging to gymnosperms in plant taxonomy.The leaves of conifers are mostly evergreen,with needle like or scaly leaves.After conifer cones mature and fall off naturally,the water content of their scales is very low,and there are a certain amount of seeds and resins inside the cones.The resins are oily and easy to burn,while the cones scales are easy to be ignited because of the low water content,and the cones burn very violently after being ignited.Because of this feature,conifer cones have been used as firewood before,so flammable conifer cones However,at present,there is no systematic study on the combustion characteristics of coniferous cones,no complete database of combustion characteristics has been formed,and there is no prevention and control measures for coniferous forest fires.In this paper,the cones of four common conifers(Korean pine,camphor pine,larch,spruce)in Northeast China forest region were analyzed by thermogravimetry and combustion experiments.The pyrolysis experiments of conifer cones were carried out to explore the combustion characteristics of different experimental objects and the effects of different heating rate,particle size and atmosphere environment on the combustion characteristics of experimental objects.The thermokinetic parameters of the experimental object can be obtained by pyrolysis experiment,and the kinetic model of the experimental object can be established.The activation energy E and frequency factor a of the experimental object can be obtained by coats Redfern dynamic analysis method,which provides the basis for the establishment of conifer cone combustion characteristics database.The combustion experiment of coniferous cones can obtain the data of combustion products,heat release rate and so on,which can provide data basis for fighting coniferous forest fire.The results show that:(1)The pyrolysis process of cones of Pinus koraiensis,Pinus sylvestris,Larix gmelini and spruce can be divided into pre heating and drying stage,pre heating stage,solid decomposition stage and residual carbon decomposition stage.Among them,the heating rate mainly affects the speed of the pyrolysis process(represented by the weight loss rate),and with the increase of heating rate,the reaction will shift to the high temperature direction,but the residual amount will increase;the material particle size mainly affects the maximum weight loss rate of pyrolysis,the larger the particle size,the greater the maximum weight loss rate of pyrolysis,and the greater the residual amount;the experimental atmosphere mainly affects the pyrolysis reaction process The pyrolysis reaction in high purity air is more thorough than that in nitrogen,and the residue is less.(2)The best mechanism function of the cones of Pinus koraiensis,larch and spruce in nitrogen atmosphere is[-ln(1-?)]4.The best mechanism function of the cones of Pinus sylvestris var.mongolica in nitrogen atmosphere is ?2.Larch has the highest activation energy and frequency factor,and needs the most heat energy for combustion.(3)The combustion of coniferous cones is a fast and violent combustion process.The oil outside the cones will accelerate the ignition process of the scales,while the scales which are dry and rich in lignin,cellulose and hemicellulose will make the cones flammable and burn violently.If the coniferous cones fall to the ground under the dry and hot weather conditions,it will cause great fire hazards to coniferous forests.