In this post, I want to share to you comparison of several pipeline flow equation. Some of you may already know that there are so many flow equations in pipeline. If you want to understand the details of each equation, I recommend you to check this book. I also use the book as reference in this post.
In general, each flow equation is function of gas flow rate, gas properties, pipeline diameter, pipeline length, and upstream and downstream pressure. There are eleven (11) flow equation described in the book.
- General flow equation
- Colebrook-White equation
- Modified Colebrook-White equation
- AGA equation
- Weymouth equation
- Panhandle A equation
- Panhandle B equation
- IGT equation
- Spitzglass equation
- Mueller equation
- Fritzsche equation
Table below summarizes application of each pipeline flow equation.
The book mentioned that the most conservative pipeline flow equation is Weymouth equation. The equation gives the lowest downstream pressure (the highest pressure drop).
Figure below shows comparison of several well-known pipeline flow equations with this condition: pipeline 100 mi long, NPS 16 with 0.250 in. wall thickness, operating at flow rate of 100 MMSCFD. The gas flowing temperature is 80oF. With the upstream pressure fixed at 1400 psig, the downstream pressure was calculated using different flow equation. Pipe roughness is 700 micro in for both AGA and Colebrook equation, whereas a pipeline efficiency of 0.95 was used in Panhandle and Weymouth equation.
Bonus!
Guys, I made a spreadsheet containing solutions of example in Chapter 2 of this book. This book truly helped me to understand the difference and approach used in each flow equation. I thought it would be useful if all process engineer got this spreadsheet. So, I want to share this spreadsheet to you.
If you wish to get the spreadsheet, please leave the comment in this link. Since the file contain Macro, I cannot share here.