Technical Evaluation of BTEX Emission Mitigation from Gas Dehydration Unit by Revamping and Using Alternative Glycols

Water removal is crucial in natural gas processing to minimize water content, ensure safe transmission, and prevent operational issues like equipment corrosion and hydrate formation. Glycol absorption could be considered as one of the most effective methods used for natural gas dehydration and dew point control. However, during solvent regeneration, some pollutants, like benzene, toluene, ethylbenzene, and xylene (BTEX), are released to the atmosphere, resulting in catastrophic physical and mental health problems. Minimizing such pollutants that have negative impacts is highly needed to avoid the related negative environmental consequences. The objective of the current work is to investigate alternative strategies targeted to minimize BTEX emissions and guarantee efficient control of the dew point. Two strategies are introduced and investigated in this work; the first strategy is based on revamping an existing unit by adding a new cooler upstream glycol inlet separator, while the second strategy is based on using alternative glycols. The proposed strategies are applied to an Egyptian natural gas dehydration unit to select the optimum scenario that achieves the minimum BTEX emissions with efficient dew point control. It is found that natural gas dehydration using monoethylene glycol (MEG) is the best scenario in reducing BTEX emissions with efficient dew point control. The impact of operating conditions on BTEX emissions, along with natural gas water content, is also investigated. Lingo optimization software, v. 18, as well as HYSYS, v. 14, are used to find the optimum operating conditions for efficient dew point control with minimum BTEX emissions. It is demonstrated that stripping gas, MEG circulation rate, and inlet feed gas temperature have remarkable effects on BTEX emissions. Two quadratic correlations are also introduced in this study to efficiently relate BTEX emissions and water dew point to the influencing operating conditions.