Separation of carbon dioxide and methane in continuous countercurrent gas centrifuges

The goal of this study is to determine the order of magnitude of the maximum achievable separation for decontaminating a natural gas well using a gas centrifuge. Previously established analytical approximations are not applicable for natural gas decontamination. Numerical simulations based on the batch case show that although the separative strength of the centrifuge is quite good, its throughput is very limited. Both enrichment and throughput are only a function of length and peripheral velocity. A centrifuge with a length of 5 m and a peripheral velocity of approximately 800 m/s would have a throughput of 0.57 mol/s and a product flow of 0.17 mol/s. These numbers are calculated with the assumption that the centrifuge is refilled and spun up instantaneously. The results for the countercurrent centrifuge show how the production rate varies as a function of internal circulation, product–feed ratio, peripheral velocity and centrifuge length and radius. Under conditions similar to those of the batch case the production is approximately half compared to the batch case, i.e., 0.08 mol/s. Optimization can yield a higher production at the cost of lower enrichment. Considering the current natural gas prices and the low production rate of the centrifuge, it is certain that the gas centrifuge will not generate enough revenue to make up for the high investment costs.