(319f) Comparative Analysis of Monoethylene Glycol (MEG) Recovery Systems

Hydrates are ice-like crystalline compounds comprised of water and natural gas, and its formation in natural gas pipelines can lead to several problems in Oil and Gas Industry, such as pipeline blockage, leading to serious operational and safety problems. To avoid these undesirable problems, the injection of hydrate inhibitors in wellheads has been widely employed. Among several options for thermodynamic hydrate inhibitors, in the present work Monoethylene Glycol (MEG) was chosen due to presenting a series of advantages when compared to other thermodynamic and non-thermodynamic inhibitors.

As MEG can be reused, its re-concentration and salt removal are necessary before recirculation through subsea pipelines, in order to avoid salts accumulation and saturation, which entails scaling and other concerns. MEG Recovery processes can be divided into three types: Traditional, Full-Stream and Slip-Stream Processes. For evaluating these processes, Aspen HYSYS® Software was used for simulation, allowing the comparison between them in terms of CAPEX, OPEX and energy consumption. Further, a better understanding is attained when a more complete thermodynamic view is taken. In this sense, a comprehensive analysis of a thermodynamic system includes both energy and exergy analyses in order to obtain a more complete picture of system behavior and, therefore, an exergy analysis was also performed.

Traditional process presented the lower values for CAPEX, OPEX and energy consumption, while Full-Stream Process presented the higher values. Slip-Stream Process occupied an intermediate position between them. However, it should be considered that Traditional Process is not a viable technology to be used in long term projects, while, undoubtedly, Full-Stream presents the greater robustness, reliability and is the most recommended for scenarios with high saline severity. Further, Slip-Stream Process can perform satisfactorily in most MEG recovery scenarios, in addition to having flexibility associated to the variation of the Slip fraction, being the most recommended option by this work for most cases.