Separating Hydrogen from Syngas (produced from the Gasification of Waste) Using Pressure Swing Adsorption – Methodology and Results

There is much interest in the production of energy from waste via gasification to produce a Syngas/Producer gas stream, containing CO, H2, CO2, CH4, H2O, and N2. From such a stream, H2 could be separated creating a clean fuel to act as an energy vector. The generation of Syngas from natural gas via Steam Methane Reforming and the application of pressure swing adsorption (PSA) to separate hydrogen from such gas is well known. Unfortunately, it was difficult to find a supplier of PSA equipment, who would on reasonable terms: (a) engage with R&D trials at a much smaller scale; (b) design for lower operating pressures; and (c) perform trials with real Syngas from waste, which will contain contaminants. Therefore, an in-house designed PSA was developed as described in this study. Since, in the waste-to-energy industry, a very high purity ‘fuel-cell’ grade of H2 is not essential, as well as for many ‘fuel-switch’ applications, an H2 purity of ~95 vol% is considered acceptable. Trials were initially performed in a long Single-Bed PSA (52 mm diameter; 8 m long). Starting with a synthetic syngas mixture, it was confirmed that H2 purity >90 vol% could easily be achieved. Then the design was scaled up to a shorter but larger diameter Twin-Bed PSA system (bed diameter: 888 mm; length1.5 m), in which an H2 purity >95 vol% was achieved using a real Syngas from a waste-to-energy gasifier (design output: 500 Nm3/h of Syngas)