6 replies to this topic

[AH1979]

I am trying to calculate the separation efficiency of a crude oil / water separator based on a required product crude specification of 0.2% water (max.). Problem is that normally separation efficiency is based on the minimum droplet size to be separated. My question is how does droplet size related to % water in the product. Eg, if a separator is sized to remove water droplets of size 150 microns, how does this correspond to the product specification of 0.2%. Does anyone have any formulas or calculators for calculating based on product spec? Alternatively does anyone know what is the correlation between water droplet size in crude oil and percentage water cut?

[Zauberberg]

Separation efficiency you will calculate by measuring residual water in crude oil. There is no formula that can give you such result - you need to perform a field measurement by obtaining a crude oil sample and see what is the actual performance of your separator.

For the other question: droplet size cannot be directly correlated to % if water in crude oil, as it will depend on the conditions upstream of the separator (flow regime, turbulence areas like valves, pumps, sudden changes of flow direction etc.), nature of the crude oil (how soluble water is in the oil), and conditions in the separator itself (i.e. residence time, presence and efficiency of separation internals, pressure, temperature). Several process design standards provide you with formulas for calculating droplet size distribution depending on some of the parameters listed above, but the best thing you can do is to make a laboratory test on the crude oil sample - there is no more accurate method than that.

[AH1979]

Thanks Zauberberg.

[KIRKProcess]

I am trying to calculate the separation efficiency of a crude oil / water separator based on a required product crude specification of 0.2% water (max.). Problem is that normally separation efficiency is based on the minimum droplet size to be separated. My question is how does droplet size related to % water in the product. Eg, if a separator is sized to remove water droplets of size 150 microns, how does this correspond to the product specification of 0.2%. Does anyone have any formulas or calculators for calculating based on product spec? Alternatively does anyone know what is the correlation between water droplet size in crude oil and percentage water cut?

Zauberberg is correct, but this has not stopped specialist equipment suppliers from determining their own generalised / proprietary relationships in the manner you are suggesting, as this is a key route to assessing theoretical performance. A lot of field work has been done over many decades to develop such relationships, which are generally not in the public domain. A typical curve would suggest removing water droplets above 150 microns from oil would leave around 2% vol carryover. To hit 0.2% you might need to go all the way down to 15-30 microns (depending on the oil properties and distribution characteristics and ignoring emulsions of course).

[MNA]

Separation efficiency you will calculate by measuring residual water in crude oil. There is no formula that can give you such result - you need to perform a field measurement by obtaining a crude oil sample and see what is the actual performance of your separator.

For the other question: droplet size cannot be directly correlated to % if water in crude oil, as it will depend on the conditions upstream of the separator (flow regime, turbulence areas like valves, pumps, sudden changes of flow direction etc.), nature of the crude oil (how soluble water is in the oil), and conditions in the separator itself (i.e. residence time, presence and efficiency of separation internals, pressure, temperature). Several process design standards provide you with formulas for calculating droplet size distribution depending on some of the parameters listed above, but the best thing you can do is to make a laboratory test on the crude oil sample - there is no more accurate method than that.

[MNA]

Hi Zauberberg

You have advised that "Several process design standards provide you with formulas for calculating droplet size distribution depending on some of the parameters listed above, but the best thing you can do is to make a laboratory test on the crude oil sample - there is no more accurate method than that."

Can you please advise from wher I can get these formulsas?

Thanks

[breizh]

Hi ,

This link may support your query :

http://www.hydroflot...f Operation.htm

As stated , the best way is to perform tests in the lab .
An other option is to ask vendor to come to your site and do pilot tests .

Hope this helps

Breizh