Identification of defluidization in fluidized bed coating using the Gaussian spectral pressure distribution
Identification of defluidization in fluidized bed coating using the Gaussian spectral pressure distribution
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DOI：
10.1016/j.powtec.2010.07.008
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发表时间：
2011-01
影响因子：
5.2
通讯作者：
M. R. Parise;Carlos A. Silva;Marcos J. Ramazini;O. Taranto
中科院分区：
文献类型：
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作者：
M. R. Parise;Carlos A. Silva;Marcos J. Ramazini;O. Taranto
在涉及流化床操作的工业应用中，部分或完全脱流是一种不希望出现的现象。在颗粒包覆过程中，如果早期检测到流化流体力学的变化，可以通过提高气速和/或降低包覆悬浮流速来防止脱流。对于工业应用来说，使用一种能够快速识别脱流区域的技术是非常重要的，可以避免效率的损失，甚至可以避免关闭过程的必要性。本文的目的是利用高斯平均频率来识别流化床涂层过程中的脱流区，这是一种基于压力波动分析的替代方法。实验在内径0.143m，高0.71m的有机玻璃柱中进行，温度为70℃。以直径为325μm、表观密度为980kg/m3的微晶纤维素（MCC）为流化颗粒，涂覆以Eudragit®为基础的悬浮液。考虑到2048个数据点，以400Hz的采样率收集了所有的静压原始数据集。所有数据采集和信号处理均采用LabView®7.1软件。结果表明，采用该方法可以清晰地识别出脱流区。它在工业应用方面也有很大的潜力，特别是在在线控制方面，以避免脱流区，从而避免涂层过程的效率损失。
The partial or complete bed defluidization is an undesired phenomenon in industrial application involving fluidized bed operations. In the process of particle coating, the defluidization can be prevented by increasing the gas velocity and/or decreasing the coating suspension flow rate, if the changes in the hydrodynamics of the fluidization are early detected. For industrial applications, the use of a technique that can quickly identify the defluidization region is very important, avoiding loss of efficiency or even the necessity of shutting down the process. The purpose of the present work is to identify the defluidization region in a fluidized bed coating process using the Gaussian mean frequency, which is an alternative methodology based on pressure fluctuation analysis. Experiments were carried out in a Plexiglas column with a 0.143m in inner diameter and 0.71m in height, at a temperature of 70°C. Microcrystalline cellulose (MCC) of 325μm in diameter and an apparent density of 980kg/m3was used as fluidizing particles, which was coated by a suspension based on Eudragit®. All raw data sets of pressure in the plenum were collected at a sampling rate of 400Hz, considering 2048 data points. LabView® 7.1 software was used for all data acquisition and signal processing. The results showed that the defluidization region can be clearly identified using the methodology employed. It also could have a high potential in industrial applications, especially for on-line control in order to avoid the defluidization region and consequently the efficiency loss of a coating process.