Opracowanie koncepcji uzyskiwania strumieni gazu o podwyższonej zawartości helu na membranach

Due to the constantly rising helium prices, resulting from the shrinking supply, reserves of helium from niche sources, including those of low quality, will become attractive. Conventional helium production technologies are energy-consuming and were designed for large streams to process (recover) helium from natural gas. Alternative technologies, e.g. using membrane separation, are being more and more often explored because of the economic benefits they can potentially have over the conventional approach. This article reviews the literature on the technologies used for membrane separation of helium from natural gas. The project was developed and a test stand was created for separation tests on membrane modules of gas mixtures with different helium content. Several series of studies were carried out with interpretation of the results of experimental dependence of the effects of helium permeate enrichment on stage cut. Simulations and calculations of the size of streams were carried out in a multi-stage helium separation system from natural gas as a function of stage cuts with retentate streams being recycled to earlier stages of separation. The concept of obtaining natural gas containing 0.3% helium gas stream with high helium content – over 90% – using membrane technology was developed. The tests were carried out on a commercially available polyimide membrane. The subsequent stages of enrichment of the gas stream in helium, 1.3, 8, 37 and over 93% helium in the final concentrate were obtained. In the high-pressure retentate stream, a helium-free product (<0.02%) was obtained which was also a gas with increased calorific value with a reduced content of carbon dioxide and nitrogen. During the experiments, a lot of effort was put into making the results broadly useful in process calculations. The general simulation problem of flow shaping (stream sizes) for a four-stage gas enrichment system on membranes has been solved. The calculation results can serve many variants depending on the flow and on stage cut Ѳ. The influence of permeate throttling pressure on separation effects was determined and the optimal range of this pressure was determined taking into account the need to compress this stream. The engineering calculations carried out for one of the variants showed the effectiveness and the possibility of its implementation. After each separation stage (degree), the permeate must be compressed again, which entails specific operating expenses related to the energy costs for compressing and cooling individual gas streams. The required power for compressing and cooling these streams was calculated.