28 replies to this topic

[opel]

The discussion is more about the Maximum velociy of a gas pipeline. I 'm wondering if somebody can also share the engineering practice of setting "Minimum" velocity that a gas transport pipeline should have? Is there some value - what 're the criteria for minimum velocity ? Thanks & Regards!

[ankur2061]

opel,

 

There is no such criteria as "minimum velocity" for transporting bone dry gas in pipelines except that it does not make economic sense transporting low volumetric flow rates for a given pipe size which would be obvious if the velocities are maintained low. 

 

However, if the gas is wet then the criteria of "minimum velocity" does make a lot of sense. At very low velocities, liquid dropout and accumulation may occur in the pipeline causing slugging, excessive and / or fluctuating pressure drop and corrosion due to water dropout and accumulation.

 

That is entirely the reason that most long-distance gas pipelines are recommended for continuous operation in the velocity range of 5-10 m/s. In real life, transportation of natural gas (sales gas) is never considered as a bone dry gas. There will always be trace quantities of water as well as heavy hydrocarbons in any sales gas and this can drop out as a liquid due to a combination of low velocity and low temperatures or any one of them.

 

Thus a minimum velocity of 1.8-2 m/s is recommended to be maintained for natural gas (sales gas) pipelines.

 

Hope this helps.

 

Regards,

Ankur.

[mech001@gmail.com]

Hi Ankur

 

I need your help on the following issues regards to the LNG piping from LNG cargo tank on an LNG vessel to the HP Pressurising Skid which is being installed for transporting the HP gas to the engine to be used a Fuel

 

1.) I need to calculate the pressure drop of the LNG pipe from the tank to the HP SKid

2.) I need to verify the LNG Pipe size from the tank & the Schedule

 

can you  please advise how should i proceed on this. What should the LNG Velocity be considered . DO i need to check the discharge velocity at the LNG intank pump

 

can i use the normal compressible fluid formula to size the pipe & the schedule

 

many thanks for your help

 

regards

Anwar

[karamipoor]

Greetings

If the speed is too low for fluid natural gas is what we are faced with a process?

Thanks

Edited by karamipoor, 22 September 2015 - 05:04 AM.