平板气升环流式光生物反应器中气泡特性的图像法分析

Analysis of bubble characteristics in a rectangular airlift loop reactor using digital image technology

气泡特性是影响气升式反应器混合、传质性能的重要参数。本文通过在MATLAB环境下编程,对采集到的气泡图像经过图像二值化、孔洞填充、气泡分割等处理,考察了不同表观气速下平板气升环流式光生物反应器内的气泡特性。研究结果表明,图像法与体积膨胀法测得的气含率结果相吻合,验证了图像处理技术测量气含率的可行性。此外,图像法还可以获得反应器内气泡的详细特征(如气泡形状、大小、分布及气液相界面积等)。通过对图像中所有气泡进行统计分析,获得了反应器中气泡的平均直径随表观气速和高度变化的规律。

The bubble characteristics play an important role in determining mass transfer and mixing in airlift loop reactor.The effect of superficial gas velocity on the bubble characteristics is investigated with developed MATLAB codes using a digital image technology （DIT） in this work.The pictures are treated with many image analysis technologies,including binary image,hole filling,overlapping bubbles segmenting and so on.The results show that the gas holdup with the method of DIT is consistent with experimental data obtained by using the developed volume expansion method.It is indicated that the DIT is feasible to acquire the gas holdup in the reactor,and the details of bubbles （including shape,diameter,distribution and interface of bubbles） can also be obtained.Through statistical analysis of all bubbles in the reactor,the changes of average bubble diameter with superficial gas velocity and height in the rectangular airlift loop reactor are addressed.