The amine unit removes hydrogen sulfide and carbon dioxide from the sour gas generated in the refinery. A sketch of the process is shown below. The sour gas from the refinery is received in the sour gas KO drum to remove any water or liquid hydrocarbons and then goes to the amine absorber. Lean amine is contacted with the sour gas and removes hydrogen sulfide and carbon dioxide. The sweet gas then exits the absorber through a sweet gas KO drum and on to the refinery fuel gas system. The rich amine from the bottom of the absorber goes to the three-phase separator, where the light hydrocarbons are flashed out of the amine and heavy hydrocarbons are separated from the amine. The rich amine is then heated in the lean/rich exchanger and fed to the regenerator column. Steam, generated in the reboiler, heats the amine and removes the hydrogen sulfide (H2S) and carbon dioxide (CO2) from the amine. The lean amine from the regenerator is cooled, in the lean/rich exchanger and the lean amine cooler, and returned to the absorber. The H2S and CO2 removed from the amine is cooled in the overhead condenser and sent to the sulfur recovery unit for processing into sulfur.
Design optimization can evaluate costs for:
- Air cooling versus cooling water exchangers
- Shell & tube versus plate & frame feed-bottoms exchanger
- Regeneration trays versus reboiler heat input
- Packing versus trays