Reduction of Sulfur Species in LNG to Ultra Low Levels

Abstract

ADNOC LNG and TechnipFMC are reviewing options to reduce total sulphur in LNG, from a current realized specification of 4-9 mgS/Nm3, down to less than 1 mgS/Nm3. The requirement is to enhance the quality of the LNG product, and reduce environmental emissions. Several technologies were reviewed, including options to hydrolyze COS present in wet sweet gas, introduction of desulphurization beds downstream the dehydration units, and changing the type of molecular sieves. Those options were extensively reviewed, and found to be inadequate on their own. Therefore, solvent swap within the Acid Gas Removal Unit (AGRU) along with Molecular sieve upgrade was found to be the most viable option. Rigorous efforts were put in place to establish a robust roadmap that serves furnishing the correct basis, defining the required assessments and developing the intended approach and tools. This paper aims to present the overall methodology, approach and efforts undertaken to study the means to reduce sulphur species in LNG, in the present three LNG trains.