Voids are important regions in some industrial processes, particularly in the iron-making process, because a void is a zone in which gas–solid heat transfer and reactions occur. This paper presents a 3D experimental study of void formation measurement with 2D projection in a packed bed using an optical method. By developing an experimental laser-attenuation scanning method, invisible voids that form in a packed bed can be detected and identified as relatively stable ellipsoids. The effects of various operational parameters on void formation are analyzed in terms of the resulting void sizes and shapes. The results show that the void shape that forms in the packed bed is close to an ellipsoid and is relatively stable. The void size is positively correlated with the blast volume rate and is negatively correlated with the blowpipe diameter. The blowpipe depth has no significant effect on either the void formation or size. The blast angle affects the void location strongly; when this angle is increased, the void moves upward. The information and methods obtained in this experiment are significant in aiding understanding of the mechanism of void formation in gas–solid reactors.

空隙是某些工业过程中的重要区域，尤其是在炼铁过程中，因为空隙是发生气固传热和反应的区域。本文介绍了使用光学方法在填充床中以二维投影测量空隙形成的3D实验研究。通过开发实验性激光衰减扫描方法，可以检测到在填充床中形成的不可见空隙并将其识别为相对稳定的椭圆体。根据产生的空隙尺寸和形状分析各种操作参数对空隙形成的影响。结果表明，在填充床中形成的空隙形状接近椭圆形并且相对稳定。空隙尺寸与鼓风量率正相关，与吹管直径负相关。吹管深度对空隙形成或大小均无显着影响。爆炸角度强烈影响空隙位置。当该角度增加时，空隙向上移动。该实验中获得的信息和方法对于帮助理解气固反应器中空洞形成的机理具有重要意义。