Technical and economic evaluation of triethylene glycol regeneration process using flash gas as stripping gas in a domestic natural gas dehydration unit

Natural gas from an underground reservoir is typically saturated with water vapor. Removal of this water vapor is required in the gas processing to avoid serious problems. This study investigated the technical and economic aspects of a triethylene glycol (TEG) regeneration unit in a domestic natural gas processing plant. This study aims to improve the performance of this dehydration unit to meet sales gas specifications while minimizing the Total Annual Cost (TAC). The important variables in this work are TEG circulation mass flow and rerouting the gas from TEG Flash Drum to TEG Regenerator as stripping gas. The flash gas, instead of discharged directly to the Flare system, is routed to the TEG Regenerator and serves as stripping gas agent to improve the TEG purity. The results revealed that utilizing flash gas as stripping gas has allowed lower TEG circulation mass flow rate and reduced the reboiler duty from 1.464 to 0.934 GJ/h (a 36.2% reduction). The TAC was reduced from $ 296 058/year to $ 236 890 /year (20.0% reduction). Through this work, a more economical design was obtained compared to the base case design.