Experimental analysis of membrane and pressure swing adsorption (PSA) for the hydrogen separation from natural gas

The current work presents a process that separates hydrogen from mixtures with natural gas transported in the natural gas grid. The aim is to achieve hydrogen at fuel cell quality (99.97% (v/v) according to ISO 14687-2:2012). Due to gas grid regulations in Austria the hydrogen content is limited to a maximum of 4% (v/v). In a hybrid approach based on membrane separation and pressure swing adsorption (PSA) the supplied high pressure hydrogen – natural gas mixture (up to 120 bar) is pre-enriched by membrane technology and further upgraded to the required quality by PSA. The majority of the feed gas is kept at grid pressure, which ensures a high energetic efficiency. The remaining components, separated by PSA, are re-compressed and returned to the grid. Beside the technological feasibility, the influence of various process parameters (e.g. stage-cut, permeate conditions, PSA hydrogen recovery) is analysed. Based on the results, the required amount of energy of 0.8–1.5 kWh/m3 (fuel-cell quality hydrogen at 25.81 bar(a)) is calculated for the so called HylyPure® process.