Flow Rate of Oil based on Pressures

[danielsonx]

I've got a system where oil is pumped at 20 bar down a pipe of 600m length into a tank at ambient pressure.
I was asked to provide an estimated maximum velocity of the oil. Temperature and viscosity of the fluids as well as pipe's diameter are known. Do you know how could I calculate it?

For natural gas there is a simple formula as on the pic below. I wonder if there's a similar formula for oil.

Thanks for your help.

 

[SNORGY]

If it is pumped, unless it is highly viscous, your flow velocity will likely be limited by the pump, I suspect. If the oil doesn't flash significantly along the way, I arrive at H = 8fLQ^2/(g(pi)^2d^5) or Q = [(Hg(pi)^2d^5)/(8fL)]^(1/2).

 

[Latexman]

Crane Technical Paper No. 410 shows how to calculate it. It is an excellent reference for many fluid flow problems. Engineers that do fluid flow calculations should own a copy.



Good luck,
Latexman

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[LittleInch]

I'm not actually convinced at the moment that this is a real scenario as 20 bar to do 600m looks very strange, but without actually telling us the pipe size or any other details it looks like a student type calcualtion to me. This is also a very high pressure drop if the flow rate is anything more than a dribble or very small tubing and could end up with a very high velocity.

However I've always found this site very useful...

http://www.engineeringtoolbox.com/darcy-weisbach-equation-d_646.html

You do also need to know or estimate the surface roughness of the pipe.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[BigInch]

Engineering toolbox method is only valid for horizontal pipes.

Independent events are seldomly independent.

 

[ione]

....horizontal,straight pipes with no fittings....

 

[danielsonx]

Thank you for your replies.

@Latexman,
Could you kindly post the equation that could be applied to this situation as I don't have access to this textbook.

@LittleInch,
It's a 4 inch pipe which discharges into a tank at that is kept at ambient pressure (discharge pressure into the tank is unknown). It's part of a bypass system that is used only occasionally. The engineering toolbox method appears to be not fit for purpose as it requires the velocity to be known.

All I know is pressure at pipe's inlet, temperature and viscosity of the oil, diameter of pipe and that the tank is kept at ambient pressure. I would like to be able to determine the max possible velocity of the fluid as one of the contractors requested that information in order to carry out some work on the system.

I've got a very limited understanding of flow conditions in such systems so your help would be greatly appreciated.

Regards

 

[Latexman]

Sorry, no, as I said, "Engineers that do fluid flow calculations should own a copy". It's available online for a nominal fee. Crane TP 410 US$60

"Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime."


Good luck,
Latexman

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[BigInch]

Daniel, all pipe flow equations have 2 primary terms, differential pressure and flowrate. If you do not know one of them, it is not the equation's fault. You must then measure or assume the missing value and solve for the other.

Independent events are seldomly independent.

 

[Latexman]

Is it a centrifugal pump? If not, what type of pump? Do you have it's "pump curve"? If so, you can calculate and plot the "system curve" on the same graph, and where the pump curve and system curve intersect, is where it will operate. If you don't have the pump curve, get the make, model, RPM, impeller diameter, etc. and find it on their website.



Good luck,
Latexman

Need help writing a question or understanding a reply? forum1529

 

[LittleInch]

If you don't know a part of the solution estimate. Hint; try 5,6,7,8,9m/sec and see which one gives you your differential pressure. A lot of things go on velocity so just try a few and see what results you get.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way