STUDY ON REACTION KINETICS OF BIOMASS PYROLYSIS

This paper deals with the test results of the study on the reaction kinetics of sawdust pyrolysis.Under the condition of different temperature rising rate,the reaction mechanism and process of biomass pyrolysis are changed.For temperature rising rate of 4.2 and 40 ℃/min,both TG-DSC-T curves are similar in their endothermal peaks.For temperature rising rate of 4.2 ℃/min over 390 ℃,chemical reaction kinetics can not be expressed by traditional mathematical model and the reaction rate appears to be in a linear relation with reaction temperature.For heating rate of 40 ℃/min within the scope of turning points(at 385-490 ℃) the reaction kinetics also can not be expressed with the mathematical model formula used usually.However for reaction temperature in the scope of 490-700 ℃,the reaction kinetics can be expressed by mathematical model with very good correlation of linear regression.The reaction activation energy of E=29.53 kJ/mol is greatly lower than the data of the usual trials(generally E=70-110 kJ/mol).For temperature rising rate of 10 and 20 ℃/min,both TG-DSC-T curves of pyrolysis reaction are similar,and their (reaction) kinetics mathematical models comform to the traditional expression method basically.These research results indicated that different heating rates determine the process of reaction.It can be deduced from test results,that the mechanism and process of fast pyrolysis reaction are different from those of the usual pyrolysis reaction,and (correspondingly) the reaction activation energy,an important physical parameter for reaction,will change significantly.