Effect Of Biomass Particles On Pulverized Coal Combustion Behavior

The most common way to use biomass energy is direct combustion,but biomass energy has the disadvantage of loose texture and large pores,good permeability leads to biomass in the combustion process is very easy to be ignited and quickly burned out,so China’s rural residents use biomass resources for cooking,heating,etc.often biomass and coal burning together to play the"ignition"and save the role of coal.And some current research shows that mixing biomass into coal for mixed combustion can improve the combustion characteristics of coal,so that ignition early combustion efficiency,and most importantly,can play a role in reducing harmful gases and carbon dioxide emissions so as to achieve energy saving and environmental protection.First,this thesis explores the combustion characteristics curves of straw and bamboo samples with different particle sizes burned by oxidation with a thermogravimetric analyzer,and analyzes the evolution of the biomass functional group structure during combustion.It was shown that aliphatic hydrogens and C=C bands were more stable at the beginning of combustion,while aromatic hydrogens were relatively stable throughout the combustion process.During the decomposition of aromatic and aliphatic hydrocarbons,the ratios of-CH3 generated and-CH3 of new radicals fluctuated little,but the general trend was that the length of the aliphatic branch gradually decreased with increasing combustion time.Secondly,according to the analysis of the experimental results of mixed combustion of biomass and pulverized coal with different particle sizes,it was found that there were differences in the mixed combustion effect of different particle sizes of biomass.The promotion effect of straw is better than that of bamboo,especially the best combustion effect of JG_R1 mixed with TSH;and the relatively good promotion effect of bamboo is ZZ_R2 and ZZ_R3.In DSX-TSH coal mixture,the addition of biomass can improve the combustion ignition point and combustion temperature,and there is no fixed rule for the promotion effect of biomass with different particle sizes.Therefore,it is necessary to consider the biomass type and particle size when choosing the biomass to coal blending,such as straw can use JG_R4 with better effect,while bamboo is better with ZZ_R2and ZZ_R3.Overall,the results of the mixed combustion experiments provide a reference for an in-depth understanding of the coal-blending combustion mechanism and the selection of suitable biomass.Finally,the study used kinetic modeling methods and microscopic characterization analysis techniques to find that the combustion of the co-blends follows three different kinetic models.The model calculations allow a more accurate description of the combustion behavior of the co-blends.The kinetic calculations show that the activation energy required for the decomposition of the co-blends in the early stages of combustion is low,which is due to the good activity of the volatile components.In contrast,the residual carbon containing stable aromatics requires more energy to initiate combustion.During the devolatilization of pulverized coal,the coal undergoes pyrolysis reactions,resulting in the destruction of oxygenated small molecules within the coal and the aromatic interstructure such as the alicyclic ring.The addition of biomass accelerates the pyrolysis process of pulverized coal and promotes the graphitization process,while the subsequent addition of bituminous coal causes the stack height to increase,further resulting in a more regular arrangement of carbon atoms.In summary,the kinetic model can more accurately describe the combustion characteristics of the co-blends,and the addition of biomass can promote the pyrolysis and graphitization processes of pulverized coal,thus improving the properties of coal combustion.