Hydrogen permeation enhancement in a Pd membrane tube system under various vacuum degrees

Hydrogen purification using palladium (Pd) membrane technology has been seen as a potential solution for producing pure hydrogen form hydrogen-rich gas. Compared to traditional practices of operating the permeate side of the membrane at atmospheric pressure, in this study, a vacuum is applied. The effects of various vacuum degrees applied to the permeate side of the Pd membrane are investigated and compared to the results under normal operation without a vacuum. The feed gas used for experiments consists of a mixture of hydrogen (70 vol%) and nitrogen (30 vol%). Three membrane operating temperatures (320, 350, and 380 degrees C), four pressure differences (2, 3, 4, and 5 atm) across the membrane, and four vacuum degrees (-15, -30, -45, and -53 kPa) applied to the permeate side are considered. For the three operating temperatures, the best improvements in the performance of hydrogen permeation are at 320 and 350 degrees C when a -53 kPa vacuum is applied, resulting in 79.4% and 79.1% improvements, respectively, compared to normal operations. Increasing temperatures leads to an increase in H2 permeation both with and without a vacuum; however, best performances of H2 permeation are observed in cases without a vacuum. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.