Biomass Pyrolysis Kinetics And Modeling And Simulation Of Particle Pyrolysis Performance

China's energy production and consumption ranks first in the world.Coal occupies the absolute dominant position of primary energy supply in China because of its abundant reserves,and the resulting CO2 is the main cause of greenhouse effect.Under the requirement of low-carbon economic development,we should change the mode of energy production and consumption in our country.For the sake of our economic development and environmental protection,it is also necessary to replace the existing energy with clean renewable energy such as biomass energy.By studying the pyrolysis kinetics of biomass,the pyrolysis kinetic parameters can be obtained,which is of great significance for understanding the reaction mechanism and optimizing the reaction conditions.On this basis,the pyrolysis model of a single biomass particle is established,and the performance related to biomass pyrolysis is obtained by numerical simulation.This paper mainly studies the pyrolysis kinetics of biomass and the numerical calculation and Simulation of biomass particle pyrolysis.Distributed activation energy model(DAEM)is usually used to characterize the pyrolysis kinetics of different types of thermoactive materials(such as coal,biomass,charcoal,polymer and solid waste).Based on the inverse problem of distributed activation energy model(DAEM),namely,estimating the distribution of activation energy of thermoactive materials from the volatile conversion curve under heating conditions,two new inversions for estimating the distribution of activation energy are proposed.One is to establish a physical and mathematical analogy between the distributed activation energy model(DAEM)and the anti-Fermi system problem in physics,and to obtain a closed approximation of the problem.The new inversion method allows the derivation of activation energy distribution function f(E)from a set of non-isothermal heating data with constant ko.Through the case study covering various model parameters,it is concluded that this method is more suitable for thermal analysis than the traditional isothermal integration method.When ?>10 kJ·mol-1,the activation energy distribution of inversion estimation is improved,and with the increase of ? value,the f(E)distribution obtained by inversion calculation is more consistent with the preset distribution.The influence of k0 value,heating rate ? and heating program on inversion estimation results is very small,which shows that the prediction of f(E)is not affected by external heating conditions.The other is to develop a new model-free method to estimate f(E)by establishing physical and mathematical analogy between the distributed activation energy model(DAEM)and the adsorption integral equation.The calculated f(E)under different activation energy function distribution parameters,heating rates and pre-exponential factors is in good agreement with the experimental data,which verifies the reliability of the method.The model parameters ? are selected between 15 and 25 kJ·mol-1,the value of k0 is 2×1010,and the condition of ?=1000 K·s-1 will make the f(E)of the inversion prediction coincide with the actual distribution better.At the same time,the above two methods can be applied to the pyrolysis analysis of complex solid materials,and can capture the multi-peak characteristics of activation energy distribution.Finally,the pyrolysis behavior of biomass was studied at particle size,and a one-dimensional unsteady pyrolysis model of spherical biomass particles was established and validated.The effects of various factors on the pyrolysis of biomass particles were investigated.The existence of thermal conductivity of particles delayed the central pyrolysis relative to the surface,but the pyrolysis process of the central and surface was similar,and the pyrolysis effect had a greater impact on the pyrolysis of large particles.The pyrolysis behavior of particles is affected to some extent by ambient temperature,particle size and radiation angle coefficient.