Pyrolysis Characteristics Of Biomass Based On Finite Element And Thermogravimetric Analysis

Energy shortage,environmental problems are increasingly obvious,research and development of clean and cheap sustainable energy is particularly important.Because of its clean,large reserves,sustainable and other advantages of biomass energy,research and development of the application of biomass energy can effectively promote the "double carbon plan".In this paper,pine sawdust,garlic straw and semi-bituminous coal were taken as the main test objects.TG 209 F3-Tarsus thermogravimetric analyzer was used to conduct thermogravimetric tests of single biomass samples and mixed samples,and TG curves and DTG curves were obtained to analyze the relationship between biomass sample quality and temperature and heating rate.The pyrolysis characteristic parameters and pyrolysis stages of each sample were analyzed to provide reference for simulation tests.According to the heating rate of TG test and the pyrolysis temperature range obtained from the test,COMSOL simulation software was used to simulate the influence of power,time and other factors on the microwave pyrolysis of biomass samples.The main research results of this paper are as follows:(1)The change of heating rate has little effect on the pyrolysis of semi-bituminous coal samples,and the residual residue of semi-bituminous coal samples after pyrolysis is the most.The temperature rise rate of 20℃/min is more suitable for 1:1 mixed pyrolysis of pine and semi-bituminous coal,but the effect of 1:1 co-pyrolysis of pine and semi-bituminous coal is not as good as their separate pyrolysis.The heating rate has a great influence on the pyrolysis of garlic straw,and higher heating rate can make the pyrolysis of garlic straw more fully.When the heating rate of pine is 40℃/min,the residue is more,so pine is not suitable for too high heating rate;The main pyrolysis stage of garlic straw is 300℃～320℃,that of pine is360℃～380℃ and that of semi-bituminous coal is 440℃～480℃.(2)The intensity distribution of the temperature field is based on the intensity distribution of the electric field.The strongest electric field temperature field of the plant biomass sample is at the port,while the strongest electric field temperature field of the semi-bituminous coal is on the surface of the vertical plane of the sample.The intensity of temperature field increases with the increase of port input power,but the high temperature area has nothing to do with the intensity of port input power,and the high temperature area increases with the increase of time.The electric and temperature fields of pine are more suitable for microwave pyrolysis.Straw absorption ability is poor,should be equipped with absorbent;The heat transfer direction of pine samples is from inside out,while the heat transfer direction of straw samples and semi-bituminous coal samples is from the surface to the inside.(3)When the heating rate is 20℃/min,the peaks of TG curves and DTG curves of the mixture of nine ratios of pine and semi-bituminous coal are the combination of the peaks of their separate TG curves and DTG curves.The pyrolysis characteristics of the two mixtures were combined,and compared with the calculated results,it was found that the mixture could promote pyrolysis.