Boosting Gas Processing Energy Efficiency by Waste Heat Recovery

Abstract

A continual improvement in energy efficiency of existing plants is imperative to achieve ADNOC target to reduce greenhouse gas emissions (GHG) intensity of operations by 25% in year 2030. The waste heat recovery (WHR) from incinerator stacks of existing Sulphur Recovery Units (SRUs) in ADNOC Gas Processing exhibits a substantial potential & contributor of energy savings and emission abatement. A high level assessment was carried out for various heat sources, results showed substantial WHR potential can be availed from SRUs. Consequently, a feasibility study was carried out to evaluate several options to recover energy from incinerator stacks of existing Sulphur Recovery Units (SRUs). The feasibility study addressed three options of recovering energy from SRUs incinerator stack exhaust; generating saturated steam, generating power and combined solution of steam & power. Those options were assessed in terms of technical feasibility and commercial viability. The study indicated that steam generation by HRSGs is technically viable and economically feasible, and considered as the best option for WHR from the existing SRU Incinerator Stacks. The WHR benefits that can be realized from just one incinerator stack by recovering the waste heat and reducing the flue gas temperature by 400 °C only (from 700 to 300 °C) are: More than 80 TPH saturated HP steam generationFuel gas savings and corresponding monetary benefitsSignificant abatement in GHG emissions The study revealed that WHR does not pose acid condensation risk due to the safe margin between the acid dew point and the actual flue gas temperature. The study also established that other constraints like pressure drop, space, tie-in location and emissions dispersion are not the showstoppers.