Key performance indicators to evaluate TSA dehydration efficiency and prevent retrograde condensation

This study addresses key operational challenges in gas dehydration units, such as liquid presence, premature breakthrough, rapid pressure drops, high energy consumption during regeneration, and adsorbent degradation. It introduces a real-time dehydration model, defines and evaluates KPIs for controlling the TSA process. The research also develops a monitoring metric for the phase envelope region where retrograde condensation occurs and validates the model industrially. Using Modelica and Python, a multicomponent natural gas adsorption drying model is created, incorporating material balance, equilibrium isotherms, pressure drop equations, and energy balance. The model accurately replicates plant data, with only 2.47% error in breakthrough time and 0.03% in adsorption capacity. Findings reveal that while water is being adsorbed, other components are minimally adsorbed; in its absence, n-butane predominates. Retained heavier hydrocarbons can lead to pore blockage and reduced adsorbent lifespan when heated during regeneration. Increased humidity and heavier hydrocarbons exacerbate bed deterioration, causing rapid pressure drops and retrograde condensation. Breakthrough time is the primary KPI for water composition changes, while the retrograde condensation monitoring metric is key for n-butane changes. This metric serves as a valuable operational constraint for industrial dehydration units, highlighting the importance of maintaining optimal temperature and monitoring inlet gas composition to prevent retrograde condensation.