The Transport Disengaging Height in the Vortexing Fluidized Bed

渦旋式流體化床之釋放高度研究

萬皓鵬(Hou-Peng Wan) ； 錢建嵩(Chien-Song Chyang)

《中原學報》 27卷1期 (1999/03) Pp. 25-34

https://doi.org/10.6358/JCYU.199903.0025

摘要

本研究於內徑0.19公尺之渦旋式流體化床冷模床中，針對粒子之「釋放高度」進行一系列之研究。細粒子之「釋放高度」對流體化床系統之設計佔有相當重要之地位。許多學者提出估算粒子「釋放高度」之關係式，但是，均未提出如何實際估算粒子「釋放高度」；本研究提出一方法，用以估算粒子之「釋放高度」。除此之外，本研究並將學者所務表之粒子「釋放高度」實驗關係式整理歸為三類：圖解法、實驗關係式法與半實驗模式法。實驗結果顯示：粒子之「釋放高度」隨一次空氣之增加、二次空氣之降低而增加，粒子「釋放高度」隨二次空氣流量之增加，呈現先降後升之趨勢，最低值出現在當二次空氣流量為1.0m^(3)/min。依據實驗數據顯示，渦旋流對於粒子之淘失速率有明顯影響，但是對於粒子「釋放高度」影響則較為不明顯。

關鍵字

釋放高度 ； 淘失 ； 渦旋式流體化床 ； 渦旋流

並列摘要

A systematic investigation on the transport disengaging height (TDH) in a vortexing fluidized bed (VFB) cold model was conducted in this study. The TDH of fine particles is an important factor in consideration of designing the fluidized bed systems. Several previous studies have been concentrating on estimating the value of the TDH, However, the method in which to determine the value of the TDH has not be defined. In this study, a method of determining the TDH can be obtained by taking the intersection point of the decreasing line of specific elutriation rate constant (K*) vs. fluidized column height (H) and the horizontal line of constant K value is reported. Besides, the correlations of the TDH, which have been reported by other researches, are well classified into three categories: graphical correlation, empirical correlation, and semi-empirical models. The experimental results of this research indicate that the TDH increases with the primary air velocity, and decreases with the secondary air velocity. The TDH is a function of the secondary air flow rate. The minimum value of TDH is obtained when the secondary air flow rate reaches 1.0 m(superscript 3)/min (14.7 m/s). Comparing experimental data in the VFB with the bubbling fluidized bed (BFB), the effect of the swirling flow on the TDH is less significant.

並列關鍵字

Transport Disengaging Height (TDH) ； Elutriation ； Vortexing Fluidized Bad (VFB) ； Swirling Flow