Process Engineering: Line Sizing
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- เผยแพร่เมื่อ 5 ต.ค. 2021
- I describe two different criteria for determining the diameter for piping: maximum velocity, and pressure drop per 100 m. The source code for the example is in a Jupyter Notebook file at
github.com/kevindorma/LineSizing - วิทยาศาสตร์และเทคโนโลยี
I've been searching for a simplified yet working version of pipe sizing, thanks for this content professor
I'm very glad to find you, keep the good work, if need any help don't hesitate. thanks professor
please prof. kevin do more of these videos ..... many thanks for your lecture
Great exp! thumbs up Sir!
This video is worth downloading
Thank you.
Sir plz do make videos on valve sizing, pump hydraulics etc
Sir plz do make videos in valve sizing, pump hydraulics etc
Very Simple and clear. Thanks a lot.
So this method is for single liquid phase only. What about two phase flow and single phase gas flow?
Using pressure drop for sizing gas flow is fine. But this only applies if the gas flow is incompressible. Velocity less than Mach 0.3 and density change less than 10%. Do not use this method for high speed gas or large DP, such as outlying pressure safety valve. And do not use for two phase. Two phase flow has other conditions that we must consider.
Great
Very informative.Since this method is applicable to single phase flow only why cant we consider darcy weisbach equation to calaculate frictional pressure drop?
This methodology is based on Darcy Weisbach. The difference is the friction factor is correlated with a different set of parameters. The standard correlation for friction factor produces a nonlinear equation in diameter. Frictional pressure drop is roughly proportional to D^5. You could use an iterative method to solve this equation.
We calculated 2 different values of the pipe diameter using Velocity and Flow Rate as constraints.
My question is, " which 1 of the 2 should be used for design purpose?".
Bigger pipes may validate with pressure drop condition, but the Velocity in the downstream, might be too less for the process to operate optimally.
Please tell
Each constraint is a value that we must not exceed. Pick the larger diameter. One example where a larger pipe is bad is slurry flow. Low velocity causes deposition. The simple rules do not apply here.
@@kevindormaconsulting4763 For single phase fluid flow, the larger pipe should be used, considering pressure drop. That means pressure drop has more weightage than Velocity.
Yes, i agree with the slurry flow. I remember in the Biogas Project, the pipe diameter was reduced from 20" to 16" from FEED to Detailed Engineering, when hydraulics were verified.
How did you find the roughness number?
Is this equation applicable for fluids?
Yes. I assume you mean a real pipeline. Something that is several km long and you want a specified pressure drop.
Respected Sir, if flowrate is too high as the objective product output is high, we would distribute flowrate in parallel pipe system, how to then find the individual flowrate of each pipe and its diamtere, considering we only have Vmax, Q (Vol flowrate) and m (mass flowrate)
We use the same approach as electric circuit with resistors in parallel. There is a current balance at each branch. Each resistor uses V=I R. With electric circuit we get a matrix equation for all V and I. With hydraulics the equations are quadratic.
Kindly guide me, I am starting calculations for Medical gas pipeline system. How to start it for a hospital?
Start with a drawing of the piping system. Show the main header for each floor, and the branch lines for each consumer. Then you need to decide the amount of DP that can be taken for the main header and the branch lines. This is always the list difficult part. What is the basis for the flow rate through the main header and each branch line? How much design margin do you want for these flow rates? These are difficult questions but very important. If the main supply is at 500 kpa then decide the pressure you can accept at each consumer. It may be 450 kpa. You can take 50 kpa for the entire path. How much DP will you permit for the main header, and how much for the small branch to consumers? You might decide 20 kpa for main header and 30 for branch. What is the piping length for main header and for the longest branch? This gives you the DP per 100 m. How much design margin do you need for each line?
Can anybody write the name of book from which he used formula for second case or please give the download link for that book.
thanks in advance it will really be a help.
Perry’s chemical engineers handbook, sixth edition, page 5-25, equation 5-65.
thankyou very much sir.
Your method of teaching is really helpful and awesome. If you have free time then please make more videos on pipe flow and piping stress analysis if possible.
Also it is request to you to recommend some TH-cam channel or suggest book covering practical pipe flow and stress analysis problems or at least share your valuable data with us.
How about the pressure loss from fittings like elbows and tees?
Line sizing is performed long before we know what the pipe route looks like. It is simply a way to choose a reasonable flow velocity. Perhaps engineers should look at this and consider the number of bends in the path and the overall pressure we can afford to lose. This might be a nice topic for a Masters Degree research project. Thanks for asking.
@@kevindormaconsulting4763 well I just asked because in duct sizing we consider the the fittings first before we size.
@@arielmcdowny2367 ahhhhhhh. An elbow has an equivalent length of about 30 duct diameter. Ducts are usually short but there may be several bends. 6 bends in a 24 inch duct is equal to 360 ft of duct. The duct may be only 50 ft long. Thanks for the knowledge.
I need 3/17ths football field size diameter
Why you are multiplying 1.3?
I was assuming that we need a design margin 30% on flow.
But one criteria should also include that is velocity head .
Kindly give me mail id, because to start the dia are 12, 15, 22,28,35,42,54,76 and 108 mm. For seven gases oxygen, carbon dioxide, nitrous oxide, medical air 4 and 7 (2 gases), vacuum and anesthesia. For these gases which dia is taken to start from plant.
Where that 1.3 comes while calculating D means (1.3×3600) that 1.3
The 1.3 is the design margin that I assumed for the flow rate (time 2:00 in the video). We always need to consider design margin, and I assumed that we need to allow for 1.3 x 50,000 kg/hr = 65,000 kg/h. This design margin depends on your situation. You may not need to provide any design margin for the flow rate. You can check the example in my blog at kevindorma.ca/2021/07/14/pipe-sizing-is-more-than-a-speed-limit/
@@kevindormaconsulting4763 you like making life easy for yourself by not explaining or deriving the equations put forth.Would it not be better if u derive the equations from first principles?
@@Tech.Library I thought I did a fair job. The use of an erosional velocity (and the C factor based on the fluid service) is from API14E. You can check the example in my blog at kevindorma.ca/2021/07/14/pipe-sizing-is-more-than-a-speed-limit/. The mathematics for the pressure drop per 100 m is from an old reference in Perry's handbook. The reference is actually an empirical correlation for the friction factor that uses pressure drop instead of Reynolds number. It is quite clever.
@@kevindormaconsulting4763 thank you for the link.
@@kevindormaconsulting4763 does pressure drop increases at an elbow joint or decreases?
NORSOK not NOROSK
I stand corrected. Thank you. They have excellent guidelines for process engineering.
Sir plz do make videos on valve sizing, pump hydraulics etc
Thank you. I don’t have a lot of time right now. I will do that when I have time.
@@kevindormaconsulting4763hello sir, is this lesson applicable for calculating the discharge line of a tank?
@@khenkhen08 Yes, but this pipe may be short. It this case you need to check the pressure drop from the entrance loss. You should also check if the drain line could produce a vortex and pull gas into the line.
@@kevindormaconsulting4763 Hello, Sir. In calculating the pipe size diameter of tank’s discharge, do i need to consider the mechanical energy balance of that tank to the tank where it will be transferred or i can just isolate and make a mechanical energy balance around the tank that I will design?