A comparative study of electrostatic current and pressure signals in a MSFC gas-solid fluidized bed
A comparative study of electrostatic current and pressure signals in a MSFC gas-solid fluidized bed
复制标题
MSFC气固流化床静电电流与压力信号的对比研究
DOI：
10.1016/j.powtec.2015.10.005
复制
发表时间：
2016
影响因子：
5.2
通讯作者：
Wang Fang
中科院分区：
文献类型：
--
作者：
Zhang Qing;Dong Kezeng;Zhou Yefeng;Huang Zhengliang;Liao Zuwei;Wang Jingdai;Yang Yongrong;Wang Fang
在气固流化床中，由于气泡运动的驱动，绝热颗粒的剧烈运动和循环导致颗粒与颗粒之间以及颗粒与壁面之间的摩擦，从而导致静电荷的产生和积累。静电信号的变化受气泡和颗粒运动的影响很大，包含了大量关于气泡行为和颗粒运动特征的动态信息。为了更全面地了解流化床中静电荷和流体力学之间的关系，有必要从静电信号中探索更多的信息。本工作构建了一个多级法拉第杯（MSFC）流化床，以同时测量每个法拉第杯的静电电流和压降。结果表明，这两种信号在时域和频域上都有很大的相似性，尤其是在床的上部。在法拉第杯中，压力降与平均空隙率成正比，同时，静电电流与平均空隙率的变化有关。进一步的分析表明，当粒子具有相同的体积和相同的电荷时，静电电流与法拉第杯压降的一阶导数成正比。这种定量关系为静电信号用于表征气固流化床中气泡行为提供了可能。
Vigorous motion and circulation of insulated particles mostly driven by bubble motions lead to repeated particle–particle and particle–wall frictions in the gas–solid fluidized bed, which result in electrostatic charge generation and accumulation. Variations of electrostatic signals are significantly affected by bubble and particle motions and contain much dynamic information on the characteristics of bubble behaviors and particle movements. It is necessary to explore more information from electrostatic signals to gain a more comprehensive understanding of the relationship between electrostatic charges and hydrodynamics in the fluidized bed. A multistage Faraday cup (MSFC) fluidized bed was constructed in this work to simultaneously measure the electrostatic current and the pressure drop of each Faraday cup. Results indicated that these two signals showed a remarkable similarity in both time domain and frequency domain, especially in the upper part of the bed. In a Faraday cup, the pressure drop is proportional to the value of the average voidage, and meanwhile, the electrostatic current is relevant to the variation of the average voidage. Further analysis demonstrated that the electrostatic current was proportional to the first-order derivative of pressure drop from a Faraday cup when particles possessed the same volume and identical charge. This quantitative relationship provides a possibility for electrostatic signal to be employed to characterize bubble behaviors in a gas–solid fluidized bed.