(277f) Effect of Packing Nonuniformity on the Performance of Hollow Fiber Membrane Gas Separation Modules Fabricated from Fiber Tows

Membrane processes are the preferred option for many gas separations. Hollow fiber membranes commonly are used in these processes. Commercial hollow fiber membrane modules often are fabricated from small groups of fibers (i.e., a tow) that are arranged into a larger cylindrical bundle.

The use of fiber tows can lead to packing non-uniformity in two ways: 1) the spacing between tows and the surrounding case and 2) the spacing between tows within the bundle. This nonuniformity can result in nonideal fluid distribution in the shell and be detrimental to module performance.

Full three-dimensional models of flow and mass transfer within fiber bundles formed from tows have been developed. These models account for the detailed fiber arrangement within modules and are solved to evaluate gas separation module performance in terms of stage cut and required membrane area as a function product gas purity for carbon capture and nitrogen production applications.

Results are presented illustrating the effects of varying fiber packing within a tow and the packing of tows. The results suggest smaller tows are preferred over larger tows, at fixed overall fiber packing, and the inter-tow packing should be comparable to the intra-tow fiber packing.

To reduce the computational cost of simulating large fiber bundles, the use of an equivalent planar bundle is proposed. A simple procedure for determining the geometry of the equivalent planar bundle is described and validated through comparisons of calculated performance metrics with results obtained from full three-dimensional simulations.