2 replies to this topic

[Milutin]

Dear all,

In our sulphuric acid alkylation unit we use caustic to wash hydrocarbon streams from acid compounds (suphates). Caustic is continuously added to process in quantity 2-2.5m³/d. Waste caustic produced is withdrawn from process and routed to waste caustic tank.
This waste caustic impose us problem because API separator pH limit (9.5 max.) - only way from waste tank is oily water sewage

Is it possible to reuse this waste caustic within refinery plants like crude distillation unit, FCC gasoline merox, or some other merox units.
Typical waste caustic lab. analysis:
Density 1.125g/cm³
NaOH content 10.77 %(m/m)
Na₂CO₃ content 0.2 %(m/m)
Na₂S content 0.0067 %(m/m)


Regards,

Milutin

[Zauberberg]

Dear Milutin, nice to see you at ChE forums.

Concerning the spent caustic problem, I would try to see if it is possible to use it as a paper industry stock. Please contact Merichem company for further information: http://www.merichem....vices/index.php
Of course, there is always an option to neutralize this process stream and route it to the wastewater treating plant, with appropriate and licensed technologies.

About reuse... I'm not sure, but your NaOH does not look so contaminated, except significant amount of sulphates. Let us hear the opinions from other forum members.

Best regards.

[P.K.Rao]

There is still life in the caustic and sulfides are less. It looks like that this caustic can be used for LPG caustic wash and pre-caustic wash of FCC gasoline. I believe Merichem has developed a process for reuse of spent caustics. You may contact them.

P.K.Rao