This project compares different enhanced TEG regeneration methods through their modeling in a commercial process simulator. Gas dehydration is important for achieving the required sales gas specifications and ensuring safe flow in the export pipelines. Usually the gas dehydration process is performed through the absorption of water vapor from the gas in the triethylene glycol (TEG), which is regenerated afterwards. The traditional regeneration method limits the achievable TEG purity, therefore also restraining the achievable dry gas quality, hence the need for enhanced TEG regeneration methods. The traditional choice was the use of stripping gas, however due to BTEX emission concerns, other enhanced regeneration methods were implemented (Vacuum, Stahl, Drizo, Coldfinger), with mixed experience by the industry.
The different TEG regeneration methods were implemented in Aspen Hysys, a widely used process simulator in the oil and gas industry, with the Glycol Package, based on the Twu-Sim-Tassone (TST) Cubic Equation of State. Based on case studies of the traditional regeneration method with or without stripping gas, it was discovered that the most relevant process parameters are the solvent circulation and the amount of stripping gas. Subsequently, case studies were conducted on each TEG regeneration model with the variation of these two parameters only. The remaining parameters were kept constant. Subsequently, for each case, an optimal set of parameters was chosen, where the required specification was met and the amount of spilled gas minimized. The methods were compared at these optimal set of parameters, based on the amount of spilled gas and the BTEX emissions, indicating the Drizo as the method with the best performance. However, regarding TEG purity, the Stahl method performed the best, achieving the highest value among all methods.