Sour water system - Query ...

[Praveen@EOL]

If any one can clear my query regarding sour water system it will be very useful ---

1.What is the necessity to treat phenolic and non- phenolic sour water seperately?
2.What will be the basic design changes in these two plant?
3.How CDU sour water is classifies as Phenolic and VDU sour water is classified as Non-Phenolic?
4.Why the product spec. of phenolica nd non-phenolic sour water in terms of ammonia differs?

Thanks in advance ... --- Praveen ...

[jdigiovanni]

1.- Because the phenols are not easily removed from the liquid stream in the stripper. Some field measurements shows 10% to 30% of incoming phenols removed. Therefore the liquid stream leaving the stripper cannot be routed to a waste water treatment (WWT). For this reason it may be necessary to have dedicated sour water stripper, where the non phenolic water can be routed to a WWT and the stripped phenolic water are routed back to the crude desalter where most of the phenols are absorbed into the crude oil.

2.- The phenolic and the non phenolic sour water stripper units are almost identical. The difference is on where the stripped water is routed

3.- As far as I know, the phenolic sour water are originated in the thermal -----ing units (Delayed Coker Unit - DCU, and Fluidized Catalytic -----ing - FCC). Probably the sour water coming from Crude Distillation Unit - CDU is classified as phenolic because this water is mainly the one coming form the desalter, where as explained in above point 1, is routed the stripped phenolic water, and in the desalter not all the phenols are absorbed (literature data indicates about 90 to 95% of entering phenols to be absorbed into the crude oil)

4.- The two product specs. differs in terms of ammonia because the phenols have a weak acid behaviour, influencing the pH of the solution, therefore at the same operating conditions (P, T and NH3/H2S concentration) and the same specific stripping steam consumption (kg of steam/ m3 of sour water) the phenolic stripper will show a better performance in terms H2S removal (removal of H2S is promoted by low pH) and a worst performance in terms of NH3 removal (removal of NH3 is inhibited by low pH).

I trust to have answer your questions

Regards