流化床-输送床耦合装置中煤颗粒的气力分级

引言流化床内颗粒与流体混合激烈,传热与传质效果好,颗粒在全床内的温度和浓度均匀一致,故流化床广泛应用于燃烧、气化及热解过程中。然而,不同粒径颗粒的流化特征有所差别,且所需要的转化时间及转化温度不同。目前的热解技术使得各粒

Pneumatic classification of coal in bottom-fluidized transport column

This work was devoted to investigating the pneumatic classification behavior of coal particles(0—10 mm)in a bottom-fluidized transport column.The tested influence parameters included superficial gas velocity of transport column, dimensionless velocity of particles, coal feeding position and rate, and internal baffle in the fluidized bottom.The classification performance was analyzed by measuring the amounts and size distributions of the elutriated particles, overflowed particles from the fluidized bed and the particles remaining in the bottom of the column.The Newton classification efficiency was used to quantitatively evaluate the classification performance.The results showed that there was an optimal dimensionless velocity for separating the fraction of particles below a given size via entrainment.With the increase of the targeted size, the Newton classification efficiency increased but the corresponding optimal dimensionless velocity gradually decreased.Feeding coal from a higher position and at lower rates facilitated the classification for small-size particles(via elutriation).The elutriated particle amount and the classification efficiency for a fraction below a given size both decreased when inserting a vertical baffle in the fluidized particles at the column bottom.