How to remove dissolved water in propane 1

[Pepijn76]

Hello,

At this moment I'm working on a project to investigate possible techniques to remove dissolved water in propane.
The only thing I can find is installing a dryer with silica gel or injecting propane to reduce the freezing point.

Are there other techniques applicable?
Does anyone have experience with removing water from propane?

Does someone have a graph where solubility of water in propane is plotted against the temperature?

 

[MiketheEngineer]

Put a tap at the bottom of the tank and drain it??

 

[Pepijn76]

We add methanol in order to prevent the present water from freezing.
But we want to get rid of the methanol. To pass the freezing test you have to remove the water.

I made some mistakes in my description:

Injecting Propane should be injecting methanol.

 

[zdas04]

The plot would be temperature and pressure, not just temperature. The GPSA Field Data Book has a series of those graphs in section 21 (Dehydration), I can't remember if Propane is one of them or not and I'm half a world away from my books right now. Dehydration of a liquid is pretty tough, if you want to gasify it, then you can use TEG contactors, deliquescent (consumable salt) dryers, mole sieves, or membrane units just like you would with any other gas.

Specific gravity of liquid propane at 60F is 0.504 (relative to water) so draining the bottom of the tank gets you a long way toward removing the bulk water. The water vapor in the vapor space is a tougher issue.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[poli60]

Pepijn76,
the following link
Link
presents the 2 alternatives to the methanol injection.
If you need a very deep removal you need to go to a Molecular Sieves adsorption system, generally TSA (twmperature switch adsorption).
It depends on the downstream application/plant. What is it?
In order to give more details you should specify the residual content of water (or water dew point) you want to achieve.
good luck

 

[Pepijn76]

Poli60,

We don't know what the downstream application is. We just store it in spheres and bullits.
We did an analysis on water content and found a watercontent of 10 and 24 ppm in 2 rundown streams, while we expected more because of the temperature of the rundowns of 23-28°C and 40-43°C respectively. Therefore I would expect 10 times as much. Maybe the free water that was formed due to the cooling down was drained of and not measured. Even if the temperature decreased to room temperature when analyzing it you would expect +/- 180 ppm.

 

[Pepijn76]

zdas04,

We don't have this book in our library. Is it possible for you to make a scan of it when you have the opportunity.

 

[zdas04]

That would be a violation of copyrights. The book costs less than $200 and I can't imagine working with hydrocarbon gases without access to a copy.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[MortenA]

This is liquid propane?, what P/T are we talking about? If its gaseous propane then im abit "revolted" thinking about it as "dissolved" water. A certain amount of water can evaporate into the gas phase and thats it. If its liquid propane, then look for the GPA/GPSA data or similar. But your methode for removing the water will be highly dependant on the volumes, state, amounts of water etc.

Best regards

Morten