Distribution Of Phenols And Pyrolysis Of Baiyinhua Lignite

Because of the shortage of hydrocarbon fuel resources in China and the abundance of coal resources,a number of varieties of rapid pyrolysis process are being developed.One of the most important pyrolysis products is phenols which are widely used in the production of polymers,drugs,antioxidants etc.Therefore,in-depth study of phenols' yield and composition is of great significance for understanding the pyrolysis mechanism,raising the engineering design level of solid hot carrier(DG Process) technique and improving its economic and environmental results.The dissertation has systematically studicd the low-temperature pyrolysis of Baiyinhua lignite.the yield of phenols.the composition and distribution of phenols.The phenols from Baiyinhua lignite tar obtained the pyrolysis process using solid heat carrier and fixed-bed experiment equipment.On the basis of large amount of experimental date,the effects of some conditions(such as pyrolytic temperature,reaction retention time,flow velocity of carrier gas and heating rate) on the yields and properties of pyrolysis products were systematically studied.The yield and basic properties of phenols,tar and semicoke change with pyrolysis conditions regularly. Baiyinhua lignite was pyrolyzed in a set of fixed-bed equipment with nitrogen as carrier gas. The highest yield of tar under the optimum pyrolysis conditions is 500℃when the flux of carrier gas is 0.3slm for 30 min.Phenols are rich in tar,accounting for 17-21%.The yield of phenols has the maximum of 3.85wt%(d) at 480℃.Complicated phenols(phenolic compounds except for simple phenols) have the higher yield than simple phenols(phenol, cresols and xylenols) when the temperature range from 420℃to 560℃.Complicated phenols account for 70%of total phenols.Compared to temperature,retention time exhibits only modest effects on the composition of phenols.Phenols and complicated phenols obtain their maxinmum when the retention time increases up to 10min at 480℃.No obvious differences in phenols yields are observed varying with the nitrogen flow velocity.The vields of phenol increase along with increasing heating rate.Based on the fixed-bed pyrolysis experiments,pyrolytic temperature was studied on the composition of phenols in lignite tar obtained by DG process.The results show that phenols have the similar law with the fixed-bed pyrolysis.Phenols and tar have the maximum yield of 3.85wt%(d) and 9.4wt%(d) both at 520℃.Phenols are rich in tar,accounting for 20-35%,and among which simple phenols account for approximately 80%.The content of phenol accounts for approximately 30%of total phenols,so does cresols.Therefore,phenols will become one of the highly profitable products in DG process.Compared the two pyrolysis process,it shows that phenols from DG process have the higher economic results,though phenols from fixed-bed have the higher yield. The reason is that DG process phenols are richer in tar and simple phenols account for 80%which centralize upon＜230℃distillation cuts and are much more useful than complicated phenols.