Abstract
One of the several challenges of the oil and natural gas offshore extraction in pre-salt reserves in Brazil, is the high content of carbon dioxide inside the wells, reaching values close to 80% in a molar fraction. This issue has a big impact on the crude extraction, due to the necessity of further expensive equipment occupying considerable deck space in platforms.
Therefore, it is necessary to research and find new technologies, which allow separating high contents of carbon dioxide at low energy consumption and low maintenance. The supersonic separation concept fulfils all these requirements due to the absence of moving parts and simple operation, because its working principle is based on the strong temperature drop of gas mixtures at supersonic expansion as it occurs in de Laval nozzles. Eventually, at the right operating conditions, the mixture starts to nucleate and, therefore, it will drive the phase change.
Nevertheless, the physical phenomena involved in this device is complex, because it involves phase change at supersonic speeds, which comprise compressible, multispecies, and multiphase flow. This paper analyses the threshold of the phase change at supersonic speeds.
The objective of this work is to calculate the influence of operation conditions (pressure, temperature and composition) in the phase change performance in supersonic separators.
The phase change was modelled using the classical theory of homogeneous nucleation. In this approach allows to estimate the phase change inside the supersonic flow for different operating conditions and allows to establish operating strategies to ensure low Mach numbers (M < 1.5) in the phase change region, allowing a further pressure recovery.
Laminar separation bubbles from a high Reynolds-number asymptotic point of view
