Comparison of ECVT and MR Measurements of Voidage in a Gas-Fluidized Bed
Comparison of ECVT and MR Measurements of Voidage in a Gas-Fluidized Bed
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DOI：
10.1021/ie8002073
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发表时间：
2009-01-07
影响因子：
4.2
通讯作者：
Gladden, L. F.
中科院分区：
文献类型：
--
作者：
Holland, D. J.;Marashdeh, Q.;Gladden, L. F.
本文首次对直径为 50 mm 的二氧化硅-氧化铝催化剂载体颗粒气体流化床 (d(p) = 58 μm) 进行磁共振 (MR) 和电容体积断层扫描 (ECVT) 的定量比较。 ECVT 数据的采集时间分辨率为 12.5 ms，标称空间分辨率为 2.5 mm x 2.5 mm x 4.5 mm。快照 MR 数据的采集时间分辨率为 26 ms，横向平面空间分辨率为 1.9 mm x 1.9 mm，轴向平面空间分辨率为 1.9 mm x 3.8 mm。这些颗粒掺有水，可产生可通过 MR 检测到的信号。这两种技术被证明可以产生定量可比较的空隙率时间平均测量值。使用这两种技术从快照图像测量的气泡频率被发现非常一致。然而，使用 MR 测量时，气泡内部的信号强度更加准确，并且使用 MR 可以更清晰地解析尾流结构。这是由于 ECVT 测量的平滑或点扩散函数的影响。 ECVT 平滑的初始估计是通过假设高斯点扩散函数来执行的。
This paper reports the first quantitative comparison of magnetic resonance (MR) and electrical capacitance volume tomography (ECVT) on a 50 mm diameter gas-fluidized bed of silica-alumina catalyst support particles (d(p) = 58 mu m). ECVT data were acquired at a temporal resolution of 12.5 ms and a nominal spatial resolution of 2.5 mm x 2.5 mm x 4.5 mm. Snapshot MR data were acquired at a temporal resolution of 26 ms and a spatial resolution of 1.9 mm x 1.9 mm in the transverse plane and 1.9 mm x 3.8 mm in the axial plane. The particles were doped with water to produce a detectable signal with MR. The two techniques are demonstrated to produce quantitatively comparable time-averaged measurements of the voidage. The bubble frequencies measured from the snapshot images using both techniques were found to be in good agreement. However, the signal intensity inside the gas bubbles was more accurate when measured with MR, and the wake structure could be more clearly resolved using MR. This was attributed to the effect of the smoothing, or point spread function, of the ECVT measurements. An initial estimate of the smoothing in the ECVT has been performed by assuming a Gaussian point spread function.