Research On Entrainment Of Pyrolysis Fly Ash Of Oil Shale And Dust Removal Performances Of Granular Bed Filter

High dust content in pyrolysis vapors of oil shale is a common issue found in solid heat carrier pyrolysis technologies.Facing the problem that high concertation dust in exit gaseous products of fluidized bed pyrolysis reactor and dust removal problem of gaseous products,the characteristics of fluidizing entrainment of pyrolysis fly ash of oil shale and filtration performances of a fixed granular bed filter?FGBF?were investigated.The purpose of this study was to provide experimental foundation for development of a dust removal plan for pyrolysis vapors of oil shale.The characteristics of fluidizing entrainment of pyrolysis fly ash of oil shale and FCC catalysts were studied contrastively by cold state experiments.Results showed that the variation of particle concentrations with axial height of these two kinds of particles were similar,particle concentrations were much denser at bottom of a fluidized bed.The average concentrations of pyrolysis fly ash in dense zone of a fluidized bed were larger than those for FCC catalysts and things were opposite in dilute zone of a fluidized bed.The TDH and gas saturated entrainment of FCC catalysts were higher than those of pyrolysis fly ash at various gas velocities.An empirical correlation for TDH and gas saturated entrainment of pyrolysis fly ash were established respectively,the computed values matched experimental values highly.The effects of gas velocity and inlet dust concentration on filtration performances of granules were investigated by cold state experiments in two beds of ceramic balls and quartz sands.Results showed that the efficiency increased at first and then decreased with increasing of dust deposition.The efficiency of high gas velocity were lower than that of low gas velocity and the efficiency decreased dramatically with increasing of gas velocity.The pressure drop increased with increasing of dust deposition and gas velocity.Certain differences also existed in filtration performances of these two kinds of granules,the efficiency of quartz sands were higher than ceramic balls in low gas velocity and the pressure drop of quartz sands were higher slightly than ceramic balls in high gas velocity.The specific mass deposit(?_ave)on the deviation degree?F and G?of dust collecting ability and pressure drop with initial values were analyzed respectively by combination with experimental datas.The efficiency and pressure drop were estimated by substituting correlations between F?G?and?_ave into the macroscopic phenomenological model,the computed values were in a good agreement with experimental values.The influences of filtration temperature,granular layer thickness and granule species of a FGBF on dust content and yield of pyrolysis products?shale oil and pyrolysis gas?were studied by hot state experiments.The dust content of pyrolysis products decreased with increasing of filtration temperature,and the dust content of shale oil increased slightly when filtration temperature exceeded 550?because of significant reduction of shale oil yield.The dust content and yield of shale oil both decreased with increasing of granular layer thickness.The yield of shale oil filtered by quartz sands increased 4⁹%compared with shale chars,but the dust content of shale oil filtered by shale chars was lower.The dust content and yield of shale oil was about1.5².5 wt.%and 7.0⁹.8 wt.%respectively with a shale chars layer of 24 mm and filtration temperature of 450⁵50?.