3 replies to this topic

[Olaniyi]

Hi all
This feels like a simple enough question but its got me stumped.

I have a pipe carrying a mixture of natural gas and liquids (say C1 - C6+ including H2Sand CO2). Suddenly the pipe has a rupture (1 cm diameter leak).

(i) How would you calculate the rate of release of liquid/gas? I've seen the formulae in the link below which include coefficeint of discharge from bernoulli's equation, but I cant find any sources for it in any of my usual texts? Does anyone have any references or better formulae to use?
http://www.engineeri...turi-d_590.html

(ii) I'm assuming that the composition of my released product will change over time. How can I assess this? How does my composition change over time?

Thanks a million!
Ogeds

[paulhorth]

Ogeds,
This problem amounts to two-phase flow through an orifice. If the pressure in the pipeline is more than about 2 bara, it will be critical flow.
For this flow problem I recommend that you use the Homogeneous Equilibrium Method (HEM). This method was developed at Imperial College, UK, by Hewitt, Richardson and Saville, in 1999 - 2000 and has been experimentally validated by them. It now forms the basis for sizing two-phase relief valves in most oil company standards. It is simple and thermodynamically rigorous.Your leakage orifice is essentially the same physical situation except the upstream pressure will decrease with time.
I suggest you read up about this calculation method via Google. Forget the venturi method, that is not relevant.

I don't think you need to worry about composition changing with time. Maybe the gas and liquid would not be uniformly mixed over the entire leakage duration, but so what?

Paul

[breizh]

Hi ,
Let you consider this resource , may not suitable for your case .

http://www.air-dispe...om/usource.html

Breizh

[Olaniyi]

Thanks!