Exergy Analysis of Monoethylene Glycol (MEG) Recovery Systems

Abstract

Abstract Hydrates are ice-like compounds comprised of water and light hydrocarbons whose formation in natural gas pipelines can lead to several problems such as pipeline blockage. To avoid these problems, the injection of Thermodynamic Hydrate Inhibitors (THI) in well-heads is widely employed. There are several options of THIs. In the present work, Monoethylene Glycol (MEG) was chosen due to its comparative advantages. As MEG can be reused, it must be re-concentrated and stripped of salts before recirculation through subsea pipelines. MEG Recovery Units (MRU) can be divided into three types: Traditional Process (TP), Full-Stream Process (FS) and Slip-Stream Process (SS). TP, FS and SS were discussed and compared via Energy and Exergy Analyses. The Exergy Analysis was based on two different approaches: firstly allocating the Reference Environmental Reservoir (RER) as the atmosphere at sea level; secondly allocating the RER as sea level atmospheric air saturated with water in equilibrium with liquid water containing MEG at infinite dilution. Those two approaches led to different results, but, in both cases TP shows the highest exergy efficiency and lowest energy consumption, while FS exhibits the lowest exergy efficiency and highest energy consumption. SS occupied an intermediate position.