Separation of hydrogen from 10 % hydrogen + methane mixtures using double-stage Vacuum Swing Adsorption (VSA)

Transportation of hydrogen by blending it to the existing natural gas infrastructure is one of the economical ways of having a green future. After co-transportation of hydrogen this way, hydrogen deblending from natural gas is needed at various locations for different end-users. Hydrogen content in pipelines at the primary injection phases will be low (<20 %) which makes the separation challenging. The goal of current study is to investigate the production of high purity hydrogen from a 10 % hydrogen + natural gas mixture using VSA. A four-bed VSA plant filled with activated carbon was used to conduct the experiments in the lab using binary mixture of 10 % H2 + CH4 (% mol/mol). High purity hydrogen (99 %) was achieved at 102 kPa feed pressure in the lab. After validation of simulation tool with experimental results, Aspen Adsorption software was used to assess the performance of producing 99 % hydrogen purity using double-stage VSA process at small scale. Results revealed that achieving high-purity hydrogen using a double-stage VSA, by upgrading H2 from 10 % to 50 % in the first stage and then to 99 % H2 in the second stage leads to better separation performance and less energy consumption than a single stage VSA for the same separation target. Afterwards, a five-bed double VSA system in industrial scale was developed using Aspen Adsorption to produce high hydrogen purity from a representative 10 % hydrogen + natural gas mixture. High purity hydrogen (>99 %) along with high recovery (>82 %) were achieved at a feed pressure of 110 kPa.