Abstract
Helium (He), the lightest inert gas, is used in various medical, scientific and industrial sectors where its global demand increases since years. The gas can be generated by nuclear fusion of hydrogen, but it is mainly found in natural gas fields at low concentrations (0.2 - 4 % (v/v)). As He is mostly required in high quality (≥ 99 % (v/v)) upgrading is necessary. For the extraction of He from natural gas, a mixture of several substances like methane, nitrogen, oxygen, carbon dioxide, other hydrocarbons, helium, hydrogen and others, several upgrading process chains are established. Commonly cryogenic distillation is used for He production due to its good economics of scale. However, as it is cost- and energy intensive the potential of several emerging technologies based on adsorption and/or membrane separation have been investigated.
As helium and hydrogen are quite comparable in terms of their separation characteristics, this work presents a process, which has been developed for hydrogen separation from natural gas, to extract helium. The hybrid process based on membrane technology and pressure swing adsorption (PSA) is investigated via process simulation. The presented results of the hybrid process (containing two membrane separation steps and a pressure swing adsorption) indicate a specific energy consumption of 0.4 to 0.7 kWh m-3 to gain Helium with 99.9 % (v/v) at 25.81 bar. Furthermore, the influence of several parameters like feed composition, chosen membrane selectivity and PSA recovery on the required amount of specific energy is shown.
