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     ADIP Liquid Hydrocarbon Treating
 
Application
The ADIP process is a regenerative process developed to selectively reduce H2S and COS to very low levels in liquid hydrocarbons such as propane-propylene (PP), LPG and NGL. The process is based on regenerative absorption with an amine solvent in contact with the acidic feed. Removal of CO2 is also possible. H2S removal from LPG or NGL down to 20 ppmwt or lower, and COS removal down to 5 ppm wt as S are achievalbe.

Description
In liquid hydrocarbon treating, for example LPG, the feed stream is contacted counter-currently with lean ADIP in a packed liquid-liquid extractor column. Co-current and counter-current mixer/settlers are used for COS removal.

The liquid hydrocarbon feed (LPG) is entering the extractor from the bottom. It is contacted with the lean solvent counter-currently. The colled lean solvent enters the extractor at the top of the column. To get rid of any COS present in the LPG, the lean solvent is partly passed to a mixer settler system together with the product LPG stream. The treated LPG passes through a coalescer to separate entrained solvent. In the lean/rich heat exchanger the rich solvent is heated by the hot lean solvent from the regenerator. Regeneration takes place in the regenerator column, which is equipped with a stripping section and one wash section in the top. The rich solvent from the lean/rich heat exchanger enters the regenerator below the wash sections and is stripped counter-currently with steam. The steam is generated in the reboiler. Low-pressure steam is used as heating medium. The top gas from the regenerator is cooled in the overhead condenser. Practically all steam present in the overhead gas is condensed. The acid gas and condensate are passed to the reflux drum from which the condensate is pumped back to the top of the regenerator by a reflux pump, in order to remove entrained solvent from the overhead gas. The acid gas, which also contains some hydrocarbons, is fed to the Sulfur Recovery Unit under pressure control. The hot lean solvent leaves the bottom of the regenerator and is pumped to the lean/rich heat exchanger by the lean solvent pump. The lean solvent from the lean/rich heat exchanger is cooled further before it is sent to the extractor column. The lean solvent is pumped from the settler to the top of the extractor column. The rich solvent from the extractor bottom is flashed to remove entrained or dissolved hydrocarbons before the solvent is sent to the regenerator via the lean/rich heat exchanger.

The treated LPG then passes through a coalescer to separate entrained ADIP solution. The rich ADIP solvent is flashed to remove entrained and/or dissolved hydrocarbons before passing to the regenerator. Stripping of the rich solvent is identical to that of gas treating.

Operating Conditions
The typical operating pressure is 20-40 bar and temperature 30 - 50 C.

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 7.700 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.

Streams to be Treated
Contaminants Removed
Natural Gas Liquids (NGL)
Liquefied Petroleum Gas (LPG) 		   H2S, COS
   H2S, COS
 

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