4 replies to this topic

[shvet]

Now I'm working on вiesel vacuum dryer revamp (increase of productivity, new is ~60 t/h) and as I found out there is some problem with diesel. Water residual has to be ~40ppmw and no more than 50 ppmw. From time to time water residual is 300-500 ppmw and operators can do nothing.

 

I would like to know more about vacuum dryers and coalescers. Can I suggest to replace vacuum dryers with something else, for example coalescer? Can anybode share information about hydrocarbon treatment from water?

[PingPong]

If your vacuum dryer does not operate properly, you should focus on solving that problem.

Start looking at operating T and P of the dryer in periods when it operates correctly (<50 ppmw), versus periods when it does not dry correctly (300-500 ppmw). Maybe there is something wrong with the vacuum system.

 

A coalescer can only remove free water droplets, not dissolved water.

 

A vacuum dryer also removes most of the dissolved water.

 

You could add a coalescer in the cold diesel line to storage to remove free water when the vacuum dryer is not operating properly, but I don't think that that will reduce the total residual water to below 50 ppmw.

[gegio1960]

Shvet

I share Pingpong advice. Vacuum drier is, for sure, the best option.

Of course, they can't meet the spec if they are either undersized or when working in upset conditions (i.e. loss of vacuum or very high water content in the feed gasoil).

Anyway, I know of refiners that obtain the dried diesel by leaving the wet diesel for long time (days) in the tanks. This could be a possibility in case of limited time upsets.

Moreover, your spec seems very conservative (usually it's 100 ppm).

How much is the productivity increase with respect to the original design for the drier? (you say 60 t/h now, but nothing about the past).

good luck

[Profe]

Hi Shvet

 

Try the following link about salt dryers: http://www.ogj.com/a...nates-haze.html

 

 

Good luck

 

Fausto

Edited by Profe, 17 September 2015 - 02:06 PM.

[shvet]

Thanks a lot, guys

 

What about adsorbtion?