Control of fluidized bed coating particles using Gaussian spectral pressure distribution
Control of fluidized bed coating particles using Gaussian spectral pressure distribution
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DOI：
10.1016/j.powtec.2011.07.007
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发表时间：
2011-10
影响因子：
5.2
通讯作者：
Carlos A. Silva;M. R. Parise;Flávio Altinier Maximiano da Silva;O. Taranto
中科院分区：
文献类型：
--
作者：
Carlos A. Silva;M. R. Parise;Flávio Altinier Maximiano da Silva;O. Taranto
流态化在化工、食品、制药等工业过程中有着广泛的应用。然而，这些方法的操作条件经常导致反流化现象或床中颗粒的完全崩溃。在流化床涂覆过程中，保持流化状态的稳定条件是非常重要的，因为水分含量过量会导致床的反流化。这项工作的目的是应用一种新的方法，称为高斯光谱压力分布，监测和控制流化床包衣过程中使用微晶纤维素作为流化颗粒的反流化现象。该工作分两个阶段进行：1）在没有控制的情况下在包衣过程的开发期间监测流化状态，和2）使用PI控制器控制气流速率和包衣悬浮液流速。进行实验，改变固体颗粒质量、涂料悬浮液流速和过量空气速度，相对于在70°C的温度下工作的最小流化速度。高斯平均频率演变示出了流化状态转变，并且其允许限定稳定状态的带（6.0Hz至7.0Hz），其用作控制器的设定点范围以操纵用于频率转换器和用于蠕动泵的命令信号。应用Paström和Hägglund [29]方法可以获得转换器的PI控制器参数，反应曲线法提供了泵PI控制器参数的初始猜测。微晶纤维素涂层的闭环实验表明，使用控制系统可以获得更好的流体动力学条件的床在没有控制的过程。
Fluidization has been used extensively in many industrial processes in chemical, food and pharmaceutical branches. However, the operational conditions of these processes frequently lead to the defluidization phenomenon or to the total collapse of the particles in the bed. The maintenance of stable conditions in the fluidization regime during fluidized bed coating processes is very important, because the moisture content excess can cause the defluidization of the bed. The objective of this work was to apply a new methodology, known as Gaussian spectral pressure distribution, to monitor and control the defluidization phenomenon in a fluidized bed coating process using microcrystalline cellulose as fluidizing particles. The work was performed in two stages: 1) monitoring of the fluidization regimes during the development of the coating process without control and 2) control of the airflow rate and of the coating suspension flow rate using PI controllers. The experiments were carried out varying solid particle mass, coating suspension flow rate and excess air velocity in relation to the minimum fluidization velocity working with a temperature of 70°C. The Gaussian mean frequency evolution showed the fluidization regime transitions and it allowed to define a band of stable regime (6.0Hz to 7.0Hz), which was used as a set-point range of the controllers to manipulate the signal of command for frequency converter and for the peristaltic pump. The application of Åström and Hägglund [29] method allowed obtaining the PI controller parameters for the converter and the reaction curve method provided an initial guess of the PI controller parameters for the pump. The experiments of microcrystalline cellulose coating in closed-loop showed that the use of a control system allowed obtaining better fluid-dynamic conditions of the bed in relation to the process without control.