Diesel Vacuum Drying

[WeiJieYap]

Can anyone provide any information on vacuum drying for diesel? operating parameters, design specifications, pfd and estimate price ? Thank you.

Background:
Designing a new diesel hydrotreater for a refinery. Using steam stripper which requires water removal for the ULSD product. Client does not prefer salt drying so we are looking at other alternative which is vacuum drying.

 

[25362]

It might interest you to read D.S.J. Jones Elements of Petroleum Processing -Wiley- on a hydrotreated diesel "stabilizer" worked example based on a fired heater reboiler to elude the need of a drier.

 

[WeiJieYap]

Thx for the reply.
yeah we have considered reboiler stripper but from the cost estimator, a fired heater will cost a lot more than a steam stripper.

 

[WeiJieYap]

Sry shud be more precise on my reply
A reboiler stripper will cost more than a steam stripper due to an additional fired heater.
I assume the price of a vacuum dryer is a lot cheaper than a fired heater.

 

[25362]

My advice would be not to assume but to check the economics of the fired-heater stripper, not just by comparing "capex" but also by including "opex" and the possibility of reducing overall refinery carbon emissions, as well as of making 250 psig steam by exploiting the sensible heat of the stripper bottoms which would probably be around 700[sup]o[/sup]F, still keeping enough heat for the exchange with fresh feed.

Of course, the size of the unit bears influence on the results of such an analysis.

 

[25362]

Depending on the size, even an electrically heated reboiler may be of practical use.

 

[RogerH]

Weijieyap
Some operating parameters, like 130-145°C, 0.10-0.15 bara in a 5-6 tray drier will give about 40-50 wtppm water in diesel. The good thing with a vac drier you can estimate the water content directly from the operating parameters.
Usually a steam stripped fractionator with a drier is cheaper than a fractionator with a heater.
But the final choice depends on many other factors than Capex