Mathematical Modeling and Process Parametric Study of CO2 Removal from Natural Gas by Hollow Fiber Membranes

Hollow fiber membranes show a great potential in natural gas sweetening by removing CO2 to meet gas grid specifications. A membrane model with high prediction accuracy is developed to model multicomponent gas transport through hollow fiber modules. The influences of hollow fiber diameter and length, and packing density on module efficiency related to pressure drops in both sides were systematically investigated based on the developed model. The total pressure drop along the length is less than 1% if the inner diameter of hollow fibers (0.6 m length) is larger than 200 μm. Moreover, the highest module packing density was found to be dependent on hollow fiber dimension, and too high packing density will cause extreme high pressure drops. Both feed CO2 concentration and pressure were found to significantly influence membrane module performance related to the required specific membrane area and hydrocarbon loss based on process parametric study of CO2 removal from natural gas. Larger pressure drops along fiber length was found for the more-permeable polyimide membranes compared to the less-permeable cellulose acetate and carbon membranes. The developed model can be used for guiding the design of efficient hollow fiber membrane modules and potentially process simulation of membrane gas separation