Impossible to Possible - Decommissioning the UAE's Oldest Oil Refinery with Zero Flaring
Authors: Alkhoori Mohamed Abbas , Al Breiki Salem Saleh , Leelamma Manoj Pankajakshan 
Published: October 2022

Decommissioning of Oil Refinery is not a regular affair, hence information on best practices being followed during facility decommissioning is not available among refining fraternity. Objective of this paper is to share the best practices demonstrated by Abu Dhabi Refinery of ADNOC, UAE during the recent decommissioning of its 85,000 BPD Refinery Complex. We have successfully decommissioned UAE's first Oil Refinery through zero flaring / zero carbon emission concept thereby demonstrated that "impossible can be made possible through meticulous conceptualization, planning & execution".

ADNOC Refining decided to decommission UAE's 45-year-old first oil refinery, named Abu Dhabi Refinery, located in Abu Dhabi from 31st Dec 21 onwards. Biggest challenge of refinery management was to execute the decommissioning plan ensuring 100% HSE, monetizing residual hydrocarbon by reprocessing, and minimize hydrocarbon flaring thereby reducing CO2 and SO2 emission to as low as reasonably possible. During the conceptualization, Operations team has put forward a new concept of "zero flaring during decommission" consist of following steps:

Flare load simulation while depressurization of each process units utilizing best available software (historical data of previous Turnaround) Sequential shutdown of Process Units based on priority & flare load Depressurize the shutdown taken units to flare header and fully recover the flared gas through Flare Gas Recovery Unit (FGRU) and utilize the recovered gas to meet heating requirement of other units Crude unit was taken shutdown at the last stage and its depressurized gas fully utilized for steam generation purpose

During the decommissioning of the refinery, Gas Oil hydrotreater, Sulfur Recovery Units were taken shutdown as a priority, seven days in advance based on flare load estimation. Subsequently, units were depressurized at a slower rate to flare header. Released gases were fully recovered utilizing FGRU and sent to fuel gas header and later it was utilized for burning purpose in Naphtha Hydrotreater (NHT), Reformer & Crude Distillation Unit (CDU). By doing so, the outsourced natural gas consumption reduced significantly.

Next priority was Reformer Unit, its system quantity was utilized for heater firing in CDU/NHT. Finally, CDU/NHT & LPG Sweetening Units were taken shutdown and its system volume utilized for steam generation.

Utilizing zero flaring concept, ADNOC Refining could productively monetize more than 500 MT of flared quantity by reducing same quantity of outsourced natural gas consumption (savings of nearly 1Million AED), which accounted for the reduction of more than 1300 MT of CO2 to the environment.

As explained decommissioning of an Oil Refinery is not a regular affair, hence information on best practices was not available among refining community. ADNOC Refining interacted with Shareholders that have performed similar decommissioning to capture their experience. With reference to process units depressurizing, all the decommissioned refineries were directly released the gas to flare and burned off. Hence with great proud we can say that "Zero flaring" concept adopted by Abu Dhabi Refinery is a novel concept and can be adopted by refineries planning for decommissioning in the future.

In addition, such concept can be productively utilized for refinery Turnarounds as well to reduce carbon reduction and save significant operating cost.