标题：Studies on fluidization characteristics of a continuous gas-solid fluidized bed with dynamic scrapers
作者：Xie, Weining; Luo, Zhenfu; He, Yaqun; Zhou, Enhui; Lv, Bo; Zhou, Nianxin; Zhu, Xiangnan
作者机构：[Xie, Weining; He, Yaqun] China Univ Min & Technol, Adv Anal & Computat Ctr, Xuzhou 221116, Jiangsu, Peoples R China.; [Luo, Zhenfu; He, Yaqun; Zhou 更多
通讯作者：Luo, Zhenfu;Luo, ZF;He, YQ
通讯作者地址：[Luo, ZF; He, YQ]China Univ Min & Technol, Sch Chem Engn & Technol, Xuzhou 221116, Jiangsu, Peoples R China.
来源：CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION
关键词：Continuous air dense medium fluidized bed; Dynamic scrapers;; Fluidization characteristics; Inhibition of gas bubbles; Minimum; fluidization velocity
摘要：Scrapers are important inner components in continuous fluidized beds in the state where they are most commonly used industry. Dynamic scrapers have significant effects on fluidization characteristics. A lab-scale continuous air dense medium fluidized bed (CADMFB) was designed, and the influences of operational parameters were studied. Moving scrapers lead to velocity gradients in the horizontal direction among magnetite particles in different bed heights, which assisted in loosening of the dense medium bed. Hence, bed pressure drop and minimum fluidization airflow rate were lower than those in beds with static scrapers. If the scraper velocity is kept constant, minimum fluidization airflow rate increases with increasing scraper distance. But the ratio of standard deviation to average bed pressure drop increases with the increase in the scraper distance, which indicates a decrease in bed stability. Minimum fluidization airflow rates also increased with increasing scraper velocities, but a fast scraper speed may also cause bed pressure fluctuations. Dynamic scrapers can inhibit the generation of big gas bubbles. Optimum scraper velocities for various scraper distances can be calculated by nu > Lg(0.6)pi(0.2)/1.43Q(0.2). Results indicate that 50 mm was the ideal scraper distance, and the optimum scraper velocity was about 0.35 m/s. Results also show that fluidization in boundary zones between dynamic scrapers and static sidewalls was worse than that of middle zones of CADMFB.