Applications
The ADIP process is a regenerative process developed to selectively reduce H2S in gas to very low concentrations, while a good selectivity for H2S in the presence of CO2 can be achieved. The ADIP process uses an aqueous solution of di-isopropanol amine (DIPA) and an aqueous solution of methyldiethanol amine (MDEA). MDEA is used for those applications in which high selectivity for H2S is required. Depending on operating conditions 20 - 60% of the CO2 is co-absorbed if DIPA is used as the ADIP solvent, while this can be reduced to 10 - 30% if MDEA is used as the solvent. The ADIP process can also be used for enrichment of acid gas feed to a sulfur recovery plant, to achieve a higher H2S content. Integration of gas treating with the SCOT solvent system is an option.

Description
The H2S containing gas is contacted counter-currently in an absorption column with ADIP solvent. The regenerated solvent is introduced at the top of the absorber. The H2S loaded solvent (rich solvent) from the absorber is heated by heat exchange with regenerated solvent and is fed back to the regenerator, where it is further heated and freed of the acid gases with steam.

The acid gases removed from the solvent in the regenerator are cooled with air or water, so that the major part of the water vapor is condensed. The sour condensate is reintroduced into the system as a reflux.

The acid gas is passed to the sulfur recovery plant (Claus plant) in which elemental sulfur is recovered from the H2S.

Operating Conditions
Absorber operating pressure can be up to 150 bar. Gas temperature can vary from ambient up to 60 C.

Features
   Reduction of H2S to very low concentrations.
   Low steam consumption and solvent circulation.
   Carbon steel equipment.
   Resistant against degradation (DIPA).
   No reclaimer required.
   Good selectivity for H2S in the presence of CO2.
   Reduced investment and operating costs compared to conventioanl designs.

References
More than 450 ADIP units ranging in capacity from 1.900 Nm3/d to 12.200.000 Nm3/d and 19 t/sd to 7700 t/sd liquid hydrocarbons are in operation throughout the world, demonstrating the reliability of the process

Licensor
Jacobs Nederland B.V., Leiden, The Netherlands, is one of the three authorized licensors on behalf of Shell Research Ltd. since 1981.