Study On Pyrolysis Characteristics And Directional Regulation Of Pyrolysis Products Of Pingshuo Bituminous Coal

Coal occupies a dominant position in our country's energy utilization.At present,the content of heavy components in coal pyrolysis tar is relatively high,which not only corrodes equipment but also restricts the development of pyrolysis industrialization.Based on this,this paper carried out the research on the pyrolysis characteristics of Pingshuo bituminous coal and the directional control of pyrolysis products.This paper firstly study pyrolysis temperature(500?900?),particle size(0.096-0.150mm,0.15-1.25mm,1.25-2mm and 2-3mm)and pyrolysis atmosphere(N₂,CH₄,H₂and CO₂)in a fixed bed experimental system on the pyrolysis characteristics of Pingshuo bituminous coal.The results show that with the increase of pyrolysis temperature,the tar yield shows a trend of"first increase and then decrease",reaching its maximum value at600?.At 500?600?,CH₄ accounts for the largest proportion of gas components,exceeding 36%.At 700?900?,H₂ accounts for the largest proportion of gas components.As the particle size increases,the yield of char increases,and the yield of tar decreases overall.Compared with N₂ atmosphere,CO₂,CH₄ and H₂ atmosphere all promote the increase of tar yield.CO₂ atmosphere increases the tar yield by about 16%on average,and the promotion effect of H₂ atmosphere is greater than that of CH₄ atmosphere.In order to get lighter tar,the influence of N₂,CH₄,H₂ atmosphere and post catalyst Ni/Al₂O₃ on the pyrolysis characteristics of Pingshuo bituminous coal was investigated in a small fluidized bed experimental system.The results show that both H₂ and CH₄atmospheres increase the yield of pyrolysis tar.Compared with CH₄ atmosphere,CH₄+Ni increases the tar yield by 10%,and pyrolysis tar tends to be lighter.Through simulated distillation and GC-MS analysis,compared with N₂ atmosphere,CH₄,H₂ atmosphere and CH₄+Ni reduce the asphalt content and increase the relative content of light oil,phenol oil,naphthalene oil,washing oil as well as anthracene oil.The amount of increase appears:CH₄+Ni>H₂>CH₄.Compared with CH₄,the polycyclic aromatic hydrocarbons and aliphatic hydrocarbons in the tar under CH₄+Ni increase,while the phenols are greatly reduced.Through elemental analysis and scanning electron microscopy(SEM)to obtain the char characteristics,it is found that H₂ and CH₄ atmospheres can remove S and N of the char,and also increase the pores and bubbles of the char structure.The catalyst was characterized by X-ray(XRD),thermogravimetry(TG),specific surface area(BET),SEM and energy spectrum analysis(EDS).It was found that the catalysts before and after the reaction contain Al₂O₃,NiAl₂O₄ and a certain degree of C.The specific surface area,pore size and pore volume of the catalyst after the reaction are all reduced compared with those before the reaction.Finally,based on the 1MW_t pilot test system,the characteristics of coal gas and tar at different pyrolysis temperatures are obtained to form a technical solution for directional control of pyrolysis products.