Using X-ray computed tomography to measure local gas holdup in a stirred tank reactor

Visualizing fluidized beds with X-rays

“…Iowa State University developed the X-ray Flow Visualization (XFloViz) facility in the Experimental Multiphase Flow Laboratory to study multiphase flows using noninvasive Xray techniques. This facility and its development have been thoroughly explained in the literature (Ford 2006;Ford et al, 2007;Heindel et al, 2005;Heindel et al, 2008;Striegel, 2005), and only a summary is provided in section 3.4. The X-ray equipment is described in the first subsection, followed by a discussion of important X-ray parameters in the second subsection.…”

“…To account for pixel non-uniformity, linear normalization is employed as outlined by Ford (2006), Heindel et al (2008), andStriegel (2005). In ideal situations, every pixel in the detector/camera pair responds identically to incident X-ray energy; however, in real-world applications pixels do not behave ideally.…”

“…The normalization essentially performed a linear interpolation, using a dark and a light image according to (Ford, 2006) an object in the imaging region using the same X-ray power settings as the test conditions. From these two files, the PS_CT imaging program automatically applies the calibration to the images during acquisition.…”

Visualizing Fluid Flows With X-Rays

“…The images in Fig. 8 are contour maps of the local CT value, which can be related to the local gas holdup [49]. The blue regions correspond to all air and the or.m~e yellow regions are nearly all water.…”

“…corrections for a phenomenon called beam hardening must also be applied [45,46]. To account for these effects, software algorithms were created to unwarp the image, normalize the pixel response, and correct for beam hardening [47,49]; more details can be found elsewhere [42].…”