Acceptable leak for achieving a gas-tight system in mixed ionic-electronic conducting membranes

Abstract

Mixed ionic-electronic conducing (MIEC) membranes have an outstanding performance for air separation because they are 100% selective to oxygen. Unfortunately, the technology is not widely used in industry due to issues related to sealing the membrane. Having a gas-tight system is important to maximize the membrane performance. Up to date, it is unclear in literature when to consider the membrane system to be a gas-tight due to the use of different experimental setup and several expressions to describe the leak. This paper presents various methods to measure the leak such as water test, differential pressure and gas content monitoring. The paper also reviews the common correlations to calculate the leak based on nitrogen or oxygen content in the product gas. It was found that most of the researchers prefer to describe the leak based on the amount of the leaked oxygen to the total permeated oxygen because of the independency of operating conditions. Majorities of the studies suggests to have no more than 1% of the leaked oxygen to achieve a leak-free system.