The exploitation of gas reserves with significant amounts of sulphur together with the tightening of commercial specifications for these compounds represents a tough challenge for operating companies. Considering the current energy scenario and the natural gas market, more efficient gas processing solutions are needed to allow the profitable commercialization of these sour gas reserves. Energy efficiency and optimal production are two strongly linked constraints for operating companies.
Chemical absorption processes based on aqueous alkanolamines solvents have been widely adopted industrially to remove CO2 and H2S from natural gas. However, these solvents show limited mercaptans removal capacity. This drawback affects the overall gas processing economics due to the need for supplementary removal steps.
To face this challenge, TOTAL has put efforts over the last decades to develop a new series of hybrid solvents able to remove, in a one-step operation, CO2, H2S and mercaptans, improving process performances without plant modification. The last developed formulation is based on a blend of MethylDiEthanolamine and Piperazine (MDEA+PZ), allowing to couple the good chemical stability of MDEA and the high performance of PZ as an activator.
Without plant modification, this new formulation has been implemented in the SOBEGI industrial sweetening unit at the Lacq site (France). This new solvent has allowed to decrease the reboiler duty of the solvent regeneration, to reduce chemicals consumption, while keeping the final product quality unchanged.
This paper describes the benefits when operating acid gas removal units with hybrid solvents. The operational feedback recorded at SOBEGI plant are presented. The benefits of using this new hybrid solvent formulation are supported by operating data collected on the plant.
The exploitation of sour gas reserves coupled with the tightening on sulphur compounds specifications in natural gas products and the increasing trend of the global natural gas demand represent a serious challenge for operating companies.
Estimations reveal that about 40% of the global remaining natural gas reserves contain acidic compounds, such as H2S, CO2, COS and mercaptans. Considering this scenario it is evident the strategic importance of natural gas sweetening for sales gas or LNG production, pointing out the need of improved and more efficient process solutions.