G. Lipscomb
"Performance of Gas Separation Hollow Fiber Membrane Modules Fabricated from Fiber Tows"
Commercial hollow fiber membrane manufacturing processes commonly use hollow fiber spinning to produce multiple fibers from one spinneret head. These fibers move together through the manufacturing process and are collected on a spool at the end of the process. This group of fibers is referred to as a fiber tow.
Modules are fabricated from fiber tows by wrapping or weaving tows to form a cylindrical bundle. Tubsesheets are formed at one or both ends of the bundle to create a module that is placed in a case for use in a separation process.
The use of fiber tows introduces two length scales in the fiber bundle: 1) the nominal spacing between fibers in the tow and 2) the nominal spacing between tows. The existence of two length scales for shell-side axial flow channels exacerbates the residence time distribution that exists in the shell-side flow which can be detrimental to performance.
The changes in residence time distribution associated with bundles of fiber tows is evaluated for a range of intra and inter-tow fiber packings. The effect increases as the packing fraction difference increases.
The effect of the residence distribution on module performance is evaluated for operating conditions anticipated for carbon dioxide capture applications from fossil-fuel fired power plants. Broadening the residence time distribution is detrimental to performance, especially as the stage cut increases.