Condensed rotational cleaning of natural gas

An increasing fraction of the world’s natural gas resources is contaminated with CO2 and H2S. This study describes the experimental verification of a novel gas separation process. The process speeds up centrifugal separation by preferentially condensing one of the components (CO2) e.g. by Joule-Thomson expansion. The mixture splits into two phases: a liquid phase which is enriched in CO2 and a gaseous phase that is enriched in methane. The liquid phase forms a mist of micron-sized particles. For normal separation, a costly high pressure low temperature section would then be required to enable droplet growth to a size where current separation technology can be applied. However the novel method, condensed contaminant centrifugal separation (C3sep) can rapidly remove the micron size particles using a rotating particle separator. The process is an option for solving the problem of the vast amounts of natural gas fields contaminated with CO2 and H2S (21% of global gas reserves), where economic production with traditional methods is not feasible. The invented process also offers the possibility for cheap and energy-efficient removal of CO2 from syngas of gasification power plants thus providing a breakthrough technology for reducing CO2 emissions by capturing it in an easily storable form. The process is demonstrated at laboratory scale for a broad range of binary CH4/CO2 gas mixtures (20-80 mole% CH4). Results of experiments confirm theoretical predictions. Some preliminary droplet measurements that are relevant for the scaling of the separation equipment are included. To reliably test the performance of the separator a larger scale test is required. The film behavior within the vertically oriented RPS element is studied analytically under influence of gravitational and centrifugal acceleration in combination with large shear forces. From the film behavior the optimal element orientation is deduced. Using the experimental results, an industrial scale prototype separator is designed to operate at field scale throughput, pressure and temperature conditions. For fast preliminary separator testing purposes, a full size model separator (based on water/air) has been built to study liquid removal and separation efficiency