Kinetic Study Of Biomass Pyrolysis And Simulation Of Particle Pyrolysis Performance

As a major coal country in the world,China has always used coal as the main source of energy.However,with the continuous reduction of non-renewable resources and the continuous increase of the greenhouse effect,there is an urgent need for new clean energy and reasonable sustainable development policies.Nowadays,clean and renewable resources such as biomass energy have increasingly replaced traditional fuels to serve our society.The biomass is derived from animal and plant wastes and accumulated animal and plant resources.It has a wide range of sources.The reserves are huge,and now,it is gradually becoming a direction of new energy research..In this paper,starting from the pyrolysis of biomass,the numerical calculation and simulation of biomass pyrolysis are carried out on the kinetic scale and particle scale.According to the most commonly used distributed activation energy model(DAEM)in pyrolysis,calculation,simplification and parameter estimation are carried out.The distributed activation energy model(DAEM)method adopts the assumption of infinite parallel first-order reactions,which has good adaptability to solid-state reactions and can accurately describe the reaction process in a wide range of temperature and heating rate.This article uses different methods to carry out Estimate the parameters in the distributed activation energy model,and use the model to calculate and simulate the particle size.First of all,according to the most commonly used Model-fitting method for parameter estimation in the current distributed activation energy model,the effective estimation of the parameters in the model is achieved through the simulated annealing algorithm,and various parameters such as pine needles,peanut shells,cotton stalks,etc.are calculated through this algorithm.The parameter estimation of the distributed activation energy model of biomass,in addition to the distributed activation energy model itself,has studied the distribution of various substances under several different distributions(Gaussian distribution,Logistic distribution,Weibull distribution,Gamma distribution,Rayleigh distribution).The calculation results show that the Model-fitting method implemented by the simulated annealing algorithm can effectively estimate the activation energy distribution of different biomass,and the results obtained are also within a reasonable range through comparison with the literature.Secondly,based on the Miura differential method and integration method proposed by others,a new parameter estimation simplification method based on the Model-free method is proposed.Our simplified method does not need to use three sets of experimental data to obtain the calculation results of the activation energy distribution function.It only needs a thermogravimetric curve to obtain the activation energy distribution function.The calculation is simpler and faster.At the same time,the key influencing factors are investigated,as mentioned above.The influence of factors,heating rate,variance,etc.on numerical simulation results,and their applications in different distributions(Gaussian distribution,Logistic distribution,Weibull distribution,etc.)and multiple peaks.The calculation results show that the method is reliable enough in estimating the activation energy distribution curve,and it will have a better prediction for the pyrolysis analysis under the parameter constraints.Finally,the distributed activation energy model was used to simulate the pyrolysis behavior of spherical single biomass particles,and the one-dimensional unsteady pyrolysis model of spherical biomass particles was established and verified.At the same time,the effects of various factors on the pyrolysis of biomass particles were investigated.The simulation results under different conditions show that the thermal resistance of the particles makes the pyrolysis of the center lag behind that of the surface,and the pyrolysis process of the center and the surface are very similar.The pyrolytic thermal effect has a greater influence on the pyrolysis and ambient temperature of the large particles.