The sour water stripper removes hydrogen sulfide and ammonia from the sour water generated in the refinery. A sketch of the process is shown below. The sour water is received from the refinery in the flash drum, where light hydrocarbons are flashed off. The sour water is then fed to the feed prep tank, where the feed is mixed and stabilized. Liquid hydrocarbons entrained in the sour water are removed in the feed prep tank.
The sour water is then heated in the feed/bottoms exchanger and fed to the stripper column. Steam, generated in the reboiler, heats the water and strips the hydrogen sulfide (H2S) and ammonia (NH3) from the water. The stripped water from the column is cooled in the feed/bottoms exchanger and in the stripped water cooler, and returned to the refinery. The H2S and NH3 removed from the sour water is cooled in the pump-around cooler system or in an overhead condenser system and sent to the sulfur recovery unit for further processing.
Design optimization can evaluate costs for:
- Air cooling versus cooling water exchangers
- Shell & tube versus plate & frame feed-bottoms exchanger
- Stripping trays versus reboiler heat input