Gas network design 1

[sergiuro]

i need some good equation for calculatind the speed and the pressure drop in a gas network
i have to made a network whit 60 nodes, about 2 km
start presure 1,5 ata Q=3500 Nmc/h and at the end point of the network presure 1,2 ata and Q at last user 300Nmc/h, i tried some software but whit unsatisfied result.

 

[BigInch]

You're probably not using the software correctly, or you need a better package. There is no easy equation to do gas network design. Its an iterative procedure that makes hand or spreadsheet calculations impractical for anything more than a 5-10 pipe network.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[CJKruger]

sergiuro,

For links to software that can easily do this for you, have a look at:

http://www.korf.co.uk/

and

http://www.korf.co.uk/korf_links.html

 

[sergiuro]

i have an execel program but i need some equation to calculate speed when i know reynolds and diameter but i dont know delta P for turbulent flow the spredsheet it,s like that:

Q diameter lenght reynolds lamda P1 P2 v(speed)


where i use reynolds=2230*(Q/diameter)
P1 =1,5 ata
P2 =P1-(lamda*lenght*v*v*rho)/2*diameter
lamda it's calculated whit precision of 7 digit after zero
using coolbrok formula

so i need V(speed)

thanks

 

[BigInch]

There are 3 unknowns. Q, P1, P2

Use the network solver to calculate those, or eliminate 2 unknowns and solve for the remaining.

3 significant figures work quite well.

V = Q/A

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[sergiuro]

thanks

in fact i know Q=3500 Nmc/h and P1=1.5 ata

 

[BigInch]

Then you have all the info you need, just find the actual volume flowing inside the pipe at both points/Area of flow.

Quick way is to convert the standard flowrate to actual flowing volume inside the pipe. To do that, get the compressibility factor z, then,

Vol_1 @ P1 & T1 = Vol_std x P1/P_atm x T1/T_std /z@P1&T1
Vol_2 @ P2 & T2 = Vol_std x P2/P_atm x T2/T_std /z@P2&T2

where z = compressibility factor

Velocity at point 1 = Vol_1/A1
Velocity at point 2 = vol_2/A2

An, the inside area of the pipe at point n.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com