Modeling and Optimization of Ion Transport Membranes for Oxygen Separation from Air

Modeling and Optimization of Ion Transport Membranes for Oxygen Separation from Air

Allyson M. Brezler, Gaurav V. Mirlekar, and Fernando V. Lima

Submitted to Topical Area: Computing and Process Control

Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV

The use of high purity oxygen instead of air in fossil fuel combustion processes can increase conversion and aid in the decrease of CO₂ and NO_x emissions. Cryogenic air separation is the current technology implemented to produce oxygen, but operation requires large energy inputs that result in high costs. Ion transport membranes (ITM) for oxygen separation is an emerging technology that can be used in place of the cryogenic process to decrease costs. Ion transport membranes separate oxygen from air by selectively allowing the oxygen ions to pass through the membrane. Ceramic membranes with a perovskite crystal structure are a well-suited material for this application. In this work, the La_0.6Sr_0.4Co_0.2Fe_0.8O_3-d (LSCF) perovskite membrane module is modeled and optimized for the implementation into a 620 MWe integrated gasification combined cycle (IGCC) power plant.

An ITM model is designed in MATLAB by performing a material balance across the membrane and applying a permeation flux equation. Preliminary results show that after optimization by employing a nonlinear programming function, the cost of a membrane required to produce 1500 mol/s of oxygen for the IGCC power plant decreased from the base case design cost. Such optimization will be further discussed to reduce the cost of the membrane. By generating a model for the cost effective membrane that is overall less expensive than current air separation units, this research will help push this technology further towards implementation into chemical and advanced energy processes.