2 replies to this topic

[Papps]

I have gone gone through SWS process. I have the following doubts in the process. If ii get it clear it will be very useful for me. Thanks in advance for sharing knowledge.

1.) What is the difference between phenolic and non-phenolic sour waters? Why it is treated differently?
2.) Is selenium and phenols coming along with sour waters removed in SWS unit? What will be the effect if it is not removed?
3.) Why phenolic stripped water used in Desalters?
4.) Why Caustic is used in Phenolic strippers?
5.) Is there any difference in phenolic and non-phenolic stripped waters in terms of specification (final)?
6.) What will be the ph, h2s, nh3 and TDS content of (feed spec) for phenolic and non-phenolic strippers?
7.) Why treated spent caustic is sent to SWS?
8.) Where two stage strippers for treating sour water is applicable?

[Technical Bard]

• Phenolic sour waters come from FCCs/cokers, where cracking processes produce phenol and other related species.
• Selenium and phenol are not removed by the SWS process as they are not volatile at stripper conditions.
• The stripped phenolic sour water is often routed to the desalter as wash water because it usually low in salt, and the phenols will be partially absorbed back into the oil - which removes them from the waste brine stream and reduces treatment costs
• Caustic is used in sour water strippers when acids (other than H2S) are present, such as HCN or HCOOH. These acids bind up NH3 and make it impossible to strip down to the target level. Adding caustic (NaOH) binds these acids and releases the NH3. It must be added appropriately to prevent capturing H2S or reducing the pH of the stripped water too far.
• Generally not in my experience
• The specs are largely dependent on the specific facility and local regulations.
• The point is that caustic is needed - some plants use fresh caustic (prefered), but if you have spent caustic from some other process that won't contaminate the waste water with even worse problem species, it can be feasible to do, which would reduce chemical costs.
• Two stage sour water strippers are used if you want to produce a clean NH3 stream because you have a use for it or you really want to keep the NH3 out of the sulfur plant.

[Santhosh Kumar_205746]

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