Water in desulphurised LGO product

[Kresimir]

We have been encountering problems with excessive water content of desulphurised LGO product from an HDS unit. After feed switch or after start of LCO addition to the LGO feed, we would experience formation of an emulsion in the HDS unit product. Attempting to resolve this problem by changing stripper operating parameters does not help. However, the problem goes away after 1-2 days of operation. The unit is equiped with a coalescer. Stripping is done by steam. Normal water content is around 200 wtppm, but during the upset it ranges from 500 - >1000 wtppm.
Please help, with any suggestions.

Kreso

 

[Milutin]

Hi Krešo,

For steam stripped diesel usual water content is in a range 500-1200ppm. You can easily check this if you take samples from CDU.
Although you didn't mentioned for coalescer position, I suppose, your coalescer is on diesel product line downstream of stripper and you take samples downstream of coalescer.
If this is true you should check is your coalescer working properly. Personally I don't have experience with coalescers.

Regards,

Milutin,

 

[25362]

The following article may shed some light:

http://www.pall.com/articles_chemical_5214.asp