Reducing Benzene Emissions in Amine-Based Gas Processing Unit at Liquified Natural Gas Plant

Abstract This paper aims to present insights gained from the Tangguh LNG plant on minimizing benzene emissions from acid gas in amine unit. The scope of this paper includes describing the efforts to reduce benzene content in acid gases, operational interventions to adjust offshore wells supplying feed gas, and tactical actions to modify key operating parameters in amine units. A systematic review was carried out to reduce the benzene content in acid gases going to the incinerator. The first focus was on the offshore well gas supply. Wells were reorganised to ensure minimal benzene in the feed gas onshore with minimal impact on the onshore unit performance. The second focus was the amine unit, adjusting parameters like circulation rate, amine strength, and activator content to enable greater benzene absorption in the sweet gases, thereby reducing the benzene in the acid gases sent to the flare. Although there were some initial challenges in determining the optimal composition for the wells—where the amine unit's performance was significantly impacted by feed gas with higher CO2 content in exchange for lower benzene content—the operational interventions were successful. Benzene in the feed gas was reduced by 23% without interrupting LNG production. The combination of adjusting amine strength and circulation rate effectively decreased benzene levels in the acid gases by 47%. This series of data demonstrates that the operational interventions have successfully reduced benzene emissions in acid gases from amine unit. These strategies will be codified into site operating procedures as best practice to continuously reduce benzene emissions from amine unit. This paper draws on Tangguh LNG's experience in controlling benzene emissions from amine unit, emphasizing two key intervention areas: adjusting well arrangements and modifying operating parameters of the amine unit. This experience offers valuable insights for other operators of amine-based gas plants aiming to minimize the acid gas emissions.