Effective strategies to reduce triethylene glycol consumption in natural gas processing plants

Abstract

Triethylene glycol (TEG) is the desiccant most frequently used in natural gas processing plants to decrease natural gas water vapor content to levels at or below those required by salable gas standards (less than 7 lb per MMSCF (112 mg/Sm3) in the U.S.). Several parameters have a significant influence on the successful operation of TEG dehydration systems. Identifying and controlling these parameters can reduce major TEG losses and temporary shutdowns of gas plants. This can be accomplished by creating standard operating procedures so that TEG is only utilized when the water vapor content of the natural gas is greater than above salable levels. In doing so, TEG needs to be stored at ideal temperatures in a manner that shields it from oxygen. Isolating the dehydration system and automating TEG dispersion based on the gas water vapor content limits TEG loss to vapor, corrosion of gas handling equipment, and operational excursions. The solutions discussed are automatic variation of TEG circulation rates, use of an inert gas in TEG storage tanks, a simplified TEG usage monitoring system, and improving the function of the flash gas separator. The results of the study show a significant reduction in operating costs for a typical gas plant if all solutions are fully implemented.