Study On The Combustion Process Analysis And Thermokinetics Of Pinus Syluestriformis

Pinus syluestriformis,also known as the Beauty pine,is a unique two-needle pine in Changbai Mountain,mainly distributed on the Northern Slope of Changbai Mountain,or near Erdaobaihe Town and in the nature reserve at an altitude of about 1100m.Due to its narrow geographical distribution and small population,it belongs to the declining population.In recent years,due to the aggravation of human destruction and forest fires,it has become endangered.China has clearly designated Pinus syluestriformis as a key protected tree species.However,there is no systematic study on pyrolysis characteristics of Pinus syluestriformis in China,and there is a lack of prevention and treatment measures for Pinus syluestriformis fire.In this paper,twigs,cones,bark and pine needles of Pinus syluestriformis were selected for pyrolysis experiment and thermodynamic analysis.The pyrolysis and combustion characteristics of different experimental objects were explored,and the effects of different conditions on the pyrolysis characteristics of experimental objects were explored by changing the heating rate,particle size and atmosphere environment respectively.According to the obtained thermodynamic parameters,A suitable thermodynamic model was selected by coats-Redfern method,and activation energy E and frequency factor A were calculated to establish A complete database of combustion characteristics of Pinus syluestriformis.The data of combustion products and heat release rate can be obtained and analyzed by conducting combustion experiments on experimental objects,providing theoretical data for the prevention and control of pines fire.The results show that:The pyrolysis process of twigs,cones,bark and needles can be divided into dehydration stage,micro-weight loss stage,main weight loss stage and carbonization stage.Among them,the higher the heating rate,the less sufficient the pyrolysis.When the heating rate was 20℃/min,the weight loss rate was 80.34%,and there is thermal hysteresis phenomenon.Particle size has little influence on the experimental results.Different experimental atmospheres have a great influence on the experimental results.In high purity air atmosphere,the pyrolysis process has two peaks,the reaction duration is longer,and the residual amount is less,The weight loss rate was 98.14%.The optimal mechanism function of twigs,cones,bark and pine needles in nitrogen atmosphere is[1-（1-α）^1/3]²,and the order of activation energy is as follows:twigs>cones>bark>pine needles.During pinus syluestriformis cones combustion,the heat release rate firstly increased and then decreased.The total heat release tends to rise but the rate of increase decreases in the second half.Oxygen concentration and carbon dioxide concentration change in the overall opposite direction.The curve of carbon monoxide concentration was complicated,which was mainly due to incomplete combustion of cones.Generally,it rose first and then fell,with two peaks in the middle process.The burning process of pinus syluestriformis cones is fast and intense,because the burning process is aggravated by the external grease of the cone scales,and the cone scales contain a large amount of lignin,cellulose and hemicellulose,which make the cone highly flammable under dry conditions.Therefore,special attention should be paid to the potential fire hazard that falling cones may bring to the pinus syluestriformis.