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Pressure Drop Formula 6

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Meksen

Meksen

Mechanical
Dec 28, 2002
1
Dear All,
Is there anybody knows that pressure drop formula(largely used) for oil/petroleum as liquid in pipeline?

thanks.

 
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i'd sent it too anyone who'd like to take a look.
 
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After all that it really didn't resemble the HW equation very much then, right?

More interesting now then is how the pipeline managed to get built with the smaller diameter. What happened there? How long did they try to run it before looping it?

BigInch[worm]-born in the trenches.
 
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dcasto, the Hazen Williams formula has the form

Pd = 4.73 x L x (Q/C)[sup]1.85[/sup] / d[sup]4.87[/sup]

where
Pd is the Pressure drop
L is the pipe length in feet
Q is the flowrate in gpm
C is the Hazen Williams friction factor
d is the pipe ID in inches

Where did you use the density? Was it only to convert the mass flowrate to the volumetric flowrate Q? How different is the density of super-critical ethylene from water? By how much did the density vary over the length of the pipeline? How did you convert the Moody friction factor into the H-W C form?

Sorry for all the questions, but I cannot see how you got a good answer with this procedure.

Katmar Software
Engineering & Risk Analysis Software
 
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The formula is delta P = rho * Lenght * friction factor * Velocity ^2 / Diameter / 2 / g

 
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The Bard got it right when he wrote

What's in a name? that which we call a rose
By any other name would smell as sweet;

You can call Darcy Weisbach whatever name your like, and it stays just as accurate.




Katmar Software
Engineering & Risk Analysis Software
 
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....And the sleuth got it right when he said, "Elementary, my dear Watson."

Leave it to Harvey to get to the bottom of the mystery and discover what did the Pipeline in: it was Henry Darcy (& Julies Weisbach helped him do it)!

Harvey, you deserve a lot more stars than my single one for the excellent detective work. I hope that tight wad, Big Inch, gives you one as well.
 
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as for the looping out come, they used an existing 4" line as the line to feed the huge new VCM plant, when they could not get the throughput, we came back and laid a new lateral that was shorter in lenght and closer to the input source so at a higher starting pressure. The plant thought they would save a buck....

And if my equation isn't the precursor to the HW equation, I apologize for being misleading. Put I love the excel sheet. Like I said, I even replace the density lookup with a density calculation using a simple direct solution for zfactor to get gas density.
 
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dcasto, thanks for coming back to us on this one. We got to the right conclusion in the end, even if we did go around the bushes a few times.

Your analysis makes a very important point, which has got a bit lost in the queries over the name. You have shown that doing a rigorous analysis, breaking the pipeline up into small sections where each one can be regarded as incompressible flow is much better than an empirical estimation like Panhandle B. Those formulas had their place when engineers didn't have spreadsheets at their fingertips, but we shouldn't use them any more. I have used your technique of simply copying a spreadsheet line down 100 or 1000 times and breaking a problem down into subsections where the properties can be regarded as constant for a multitude of problems - not just fluid flow.

The Hazen Williams formula (the real one!) is of a similar nature to Panhandle B in that it is an empirical estimation. It was derived for water, whereas Panhandle belongs to the petroleum industry. We sometimes lose sight of just how much genius there is in the Darcy Weisbach analysis because it looks so simple and we use it every day, but it replaces and improves on a myriad of old formulas. It is one of the great triumphs of engineering.

Meksen, if you are still following this thread after we highjacked it, in the end the thread has answered your original query quite well - stick to the real thing and use Darcy Weisbach and don't be drawn into using any of the old estimation formulas. Buy a copy of Crane (did I say that before???). Good luck.

Katmar Software
Engineering & Risk Analysis Software
 
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Guys,

I knew from the very second dc said "HW", that he was messing around with us. Look at "how" I asked the question. The rest just confirmed my suspicions. I simply resisted the urge to push that directly and went for the more interesting story.

Monte,

[COLOR=white red]TIGHTWAD! ??? [/color] I just checked this. Monte, the rate at which you hand them out is 14% of my rate. You see, you've given 96 votes and have been a member since 2001 (2005 days) for a rate of 0.0179 votes/day, me only a member for just 130 days, but I've given 45 votes already! Rate: 0.346 votes/day. Hey just kidding. Noticed you're in Spring. I learned to fly out at the old Collier and DWH airfields, pumped jet into Arnold Palmer's Lear at DWH in 1968, and I even told him... thank you.

As for all the rest of you, change to Churchill and you'll all be in much better humor when you don't have to make any friction factor iterations.



BigInch[worm]-born in the trenches.
 
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BigInch:

Just wanted to pull your chain & see if you were awake. You killed me with your logic and facts - just like Darcy-Weisbach.

Try Serghides for explicit calculation of the Darcy Friction Factor. I think you'll like the accuracy and the simplicity. I think Harvey is a Churchill man also.

Have a good day. I think we've sold enough copies of Crane's Tech Paper #410 for the duration of the week.
 
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Before I discovered Churchill, I made an Excel sheet and programmed 4 Ff iterations into only one cell. Made it much less of a white space consumer when I broke the pipelines up into 1000 m segments and pasted right. Then I had room for the pump station curves and head-flow iterations. I added the Churchill equation next to the Colebrook cell and they cross-checked each other for a couple of years. Always got the same answers, so I stuck with it.

Is there a commission on those sales?

BigInch[worm]-born in the trenches.
 
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Guys,

I would never trust detection and engineering go hand in hand, for engineering is more human[wink]. The least thing I like is, great engineers (you three) becoming sleuths. Are the Bond girls tempting?

However, I couldn't resist myself giving BigInch a star.

 
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Guys or should I say Uncles

I recently passed my Diploma and was given this forum by one of our client and everytime I visited it, it encouraged me to go back to school and study further

Thanks all for all your discussions


 
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