Development of a Method of Evaluating Mechanical Properties of Aerated Powder

点击翻译按钮获取中文摘要

Equipments for measuring the adhesive and aggromarative properties of aerated powder were manufactured and the relations between these properties and the flow characteristics of bed such as bubbling, channeling and agglomerating fluidization were investigated by using the equipments.The following results were obtained.(1) Results by using a three dimensional fluidized bedFluidization tests including the measurement of bed pressure drop and visual observation were conducted for fused alumina powder with various particle size. The results were as follows :1) Three types of fluidization pattern exist for fine powder ; Type A : channeling at lower gas velocity followed by bubbling (complete fluidization) at high gas velocity Type B : crack-forming at lower gas velocity followed by the formation of domes where aggromarating particles are fluidized Type C : dome-forming at lower gas velocity followed by bubbling at higher gas velocityThe following "Fluidization Index (FI)" proposed in this research is effective for evaluating a mechanical property of aerated powder.uc : complete fluidization velocity up : settling velocity DELTAP : pressure drop W : powder weight A : bed cross section3) FI is closely related to spatula angle as an index of adhesiveness of powder.(2) Results by using a two dimensional fluidized bedFluidization tests of type A-powder were conducted. The following were obtained.1) Bubbles form at the tip of channels. Channel height decreases with gas velocity.2) The size of bubbles formed is independent of gas velocity and channel height, and is inherent to powder particles.3) The size of bubbles formed increases with FI.4) The experimental results of channel height is well described by an estimative model proposed in this research.