An optical method of experimentally quantifying the coating progress in a laboratory prismatic spouted bed is presented. Microcrystalline cellulose particles with size d_p = 0.57 mm are used as core material. Waterborne coating suspensions with methylene blue as a dye are used and sprayed via a two-fluid nozzle in bottom-spray configuration. A high-speed camera with a color filter is positioned in front of the observation window of the three-dimensional plant and records the flow pattern in the process chamber with a certain frequency. With increasing surface coverage, the particles become bluer and darker. The change in brightness is detected by digital image analysis. In the implemented algorithm, the spherical particles are detected, cut from the background and normalized regarding their lighting and area. The detection of coated pixels on the single particles allows the calculation of the coating fraction and coating uniformity after a Kalman filter has been applied to reduce noise. It is shown that the method can be used to determine the time needed to reach the maximum blue value indicating a complete coating of the particle bed. Besides the minimum coating duration, information on the spraying performance (e.g., the time point of a possibly occurring blockage of the nozzle) can be obtained from the data. Two exemplary experiments are presented, showing a connection of the slope of the coating fraction and the uniformity of the coating of the particles in the apparatus that results in the recommendation of a slow liquid injection for obtaining consistent coating layers as desired in many applications.

提出了一种光学方法，用于对实验室棱柱形喷头床中的涂层进度进行实验量化。d _p的微晶纤维素颗粒 = 0.57毫米用作芯材。使用以亚甲蓝为染料的水性涂料悬浮液，并通过双流体喷嘴以底部喷雾的形式进行喷涂。带有彩色滤光片的高速摄像机位于三维工厂的观察窗的前面，并以一定的频率记录处理室中的流态。随着表面覆盖率的增加，颗粒变得越来越蓝和越来越暗。通过数字图像分析来检测亮度的变化。在实施的算法中，检测球形粒子，将其从背景中切出并对其照明和面积进行归一化。检测单个颗粒上的涂层像素后，可以在应用卡尔曼滤波器降低噪声后计算涂层分数和涂层均匀性。结果表明，该方法可用于确定达到最大蓝色值所需的时间，该最大蓝色值表明颗粒床已完全被覆。除了最小的涂覆持续时间之外，还可以从数据中获得关于喷涂性能的信息（例如，可能发生的喷嘴堵塞的时间点）。提出了两个示例性实验，显示了设备中涂层分数的斜率和颗粒涂层的均匀性之间的联系，这导致推荐缓慢的液体注入以获得许多应用中所需的一致的涂层。可从数据中获取喷嘴可能发生堵塞的时间点）。提出了两个示例性实验，显示了设备中涂层分数的斜率和颗粒涂层的均匀性之间的联系，这导致推荐缓慢的液体注入以获得许多应用中所需的一致的涂层。可从数据中获取喷嘴可能发生堵塞的时间点）。提出了两个示例性实验，显示了设备中涂层分数的斜率和颗粒涂层的均匀性之间的联系，这导致推荐缓慢的液体注入以获得许多应用中所需的一致的涂层。