Evaluation and simulation of eco-technical study of the membrane separation of hydrogen from hydrogen/methane/ethylene mixture

Hydrogen can separate through several techniques, such as pressure swing adsorption (PSA), cryogenic distillation, or membrane separation. PSA and cryogenic distillation processes are commercially available separation techniques. However, they are energy intensive. Membranerelatedprocesses are considered as one of the most promising technologies for the production ofhigh-purity hydrogen. It can provide an attractive alternative to PSA and cryogenic distillation,depending upon the purity and scale of production. Furthermore, membrane separation processes consume less energy with the possibility of continuous operation. In this study we evaluated the membrane separation technology for unique case by eco-technical factors. In this case, the feedstock line contain: 3-7 % mole hydrogen, minimum 59 % methane, maximum 33 % ethylene and less than 1% ethane with 1000 kg/hr mass flow rate at 31.5 bara was subjected to separation process to reduce the hydrogen content to less than 3 % mole in product stream. so the technical study showed that best choice for this case was membrane technology, because it suitable for lowpurity and high pressure condition. Simulation revealed that optimum membrane area for this case was 270 m2, but we assumed 300 m2, due to considering safety factor. Economical study carried out based on simulation data. Calculated capital cost of membrane separation unit was 400thousand dollar. Economical study showed that investment payout is less than 1 year. Positive net present value (NPV) for next 10 years and high return on investment (about 109%), showed that this choice is economically affordable for this case.

Keywords:

membrane separation , PSA , cryogenic , separation hydrogen from methane , ethylene mixture , eco-technical study