Experimental assessment of acid gas energy recovery potential in refinery operations

Sour and acid gas streams generated during crude oil refining are commonly flared, representing both an environmental liability and an underutilized energy resource. This study experimentally evaluates the feasibility of utilizing the acid gas from the Esmeraldas Refinery in Ecuador, as an alternative energy source for on-site power generation, addressing the combined challenges of flaring reduction and energy efficiency improvement. A comprehensive physicochemical characterization based on gas chromatography, together with mass and energy balance analyses, was conducted under real operating conditions over a 48-month period. The evaluated acid gas stream exhibited a higher heating value of 3,477.73 kcal/kg and a stable average mass flow rate of approximately 52.5 ton/day. Assuming a conservative global conversion efficiency of 15%, the recoverable energy potential was estimated at at 33,466.88 kWh/day, corresponding to an equivalent substitution of 261.46 bbl/day of Fuel Oil No. 6 or 10.17% of the refinery’s current fuel and energy demand. Uncertainty and sensitivity analyses confirmed the robustness of the proposed energetic model, with propagated deviations below 0.3%, identifying conversion efficiency (η) as the dominant parameter influencing overall performance. Assuming the integration of a Claus-based sulfur recovery scheme enables the production of approximately 42.3 ton/day of elemental sulfur, supporting by-product valorization within a circular-economy framework. These results demonstrate that acid gas recovery constitutes a technically viable, environmentally complaint, and replicable strategy for refinery energy optimization, extending prior studies through long-term industrial validation under real operating conditions and an integrated energy-sulfur framework, which remains largely unexplored for developing-region refineries.