Research

When there are three phases dynamically moving, such as in a slurry bubble column, three phases fluidized bed, liquid-liquid-solid system, single source CT is not sufficient to measure time averaged cross sectional distribution of the three phases along the bed height. Therefore, dual energy/source gamma ray computed tomography is needed which is available in our laboratory. It has been developed and used to measure the time averaged cross-sectional phase distribution of three phase systems where the phases are dynamically moving. For each step of rotation, the detectors can be moved in a fine movement to produce more projection to enhance the special resolution. Depending on the detector collimation and the object to be scanned the spatial resolution can be about 1-2 mm. For each selected cross section along the reactor, the DSCT scan is usually performed for at least 2 hours or more depending on the column diameter to obtain time-averaged phase distribution of phases in good statistics. Image reconstruction is performed with software based on the Estimation-Maximization (EM) and Alternating Minimization algorithms. Advanced mathematical methodologies, algorithms and programs have been developed in-house and implemented along with the needed post-processing data to reconstruct the phase densities/holdups distribution. This technique if it is not rotated can be used as gamma ray densitometry.