Bubble Characteristics in a Fluidized Bed Stripper for Three Types of Internals

A variety of standard and proprietary baffles are used in commercial fluidized bed strippers. The most common ones are disk and donut trays, horizontal sheds (also called 'chevrons'), structured packings and horizontal subway gratings. Gratings have not commonly been used but are now attracting more interest because they are easier to install, easier to service, have higher open areas and are less prone to flooding. The functions of any stripper internal are to suppress bubble growth, enhance bubbles distribution over the entire column cross section, slow down the bubbles and/or lengthen the time solids spend in the stripper to enhance mass transfer across the phases. This paper discusses local bubble properties measured in a fluidized bed stripper for three types of internals: gratings, disk and donuts and horizontal sheds. The test material was FCC catalyst.