Cs-137γ射线CT测量标准Rushton搅拌釜气含率分布及数字图像重建

Measurement of Gas Hold-up Distribution and Digital Color Image Reconstruction for Standard Gas-liquid Rushton Stirred Tank with Cs-137 γ-CT

对一个Cs-137辐射源、7个扇型排列探测器旋转方式的γ射线CT测量气液反应釜气含率分布实验装置作了介绍,建立了该实验装置测量气含率分布和数字彩色图像重建的数学模型,并对20cm内直径的标准Rushton气液搅拌釜进行了空釜扫描验证实验和气液搅拌两种状态的比较实验。实验结果证明该CT实验装置测量结果准确,所形成气液两相气含率分布数字彩色图像清晰可辨,空间分辨率可达2mm。为了进一步进行气含率分布的定量比较,列出了平均气含率沿无因次半径的变化曲线。

An experimental γ- CT set-up with a rotating source of 100 mCi Cs-137 and seven sector-ranked detectors used for the measurement of the gas bold-up in a standard gas-liquid Rushton stirred tank with 20 cm i.d. was introduced. The mathematical models both for the measurement of the gas hold-up and for image reconstruction of γ- CT were established. Scans for the empty tank and the tanks filled with gas-liquid and operating at two different stirring speeds were conducted with γ- CT, respectively. The results show that the CT images obtained correspond completely to the actual dimensions of the tank, i.e., the size of the tank diameter, the tank wall thickness and the shaft diameter. The color CT images obtained are very clear and the space resolving power could reach 2 ram. These results confirm the usefulness and veracity of γ- CT scan used for the gas-liquid stirred tank. In order to quantitatively compare the distributions of gas hold-up under different stirring speeds, the curves describing the change of gas bold-up along the dimensionless radius under a given stirring speed were given.