Leak Rate

[moswitch]

Ladies and Gentlemen I'm attempting to model the scenario described in the attached document. Ultimately what I'm attempting to do is estimate product loss in dollars in the event of a line rupture, in order for me to do so I have to first calculate the leak volume (product released) for a full line natural gas line rupture over a 10 minute period. In the attached document I've made an attempt to use the formula on page two but I'm not confident my Actual Cubic Feet to Standard Cubic Feet is accurate. Your comments would be much appreciated!

 

[moswitch]

Problem solved.

 

[sailoday28]

It would be interesting to see the major steps taken in your solution.

 

[Latexman]

Your reference is about risk assessment, which is VERY conservative, however what you are "attempting to do is estimate product loss in dollars in the event of a line rupture". Your customer and his lawyer may have an opinion on that conservative methodology!

Without a detailed description and/or sketch, we really cannot comment on how far off this methodology is from reality. Depending on the specific situation, it could be highly accurate or it could be off by a factor of 1000!

Good luck,
Latexman

 

[moswitch]

Latexman,

Your right the method which I am trying to utilize is very conservative. Based on this method if I can determine the volume of Gas release (Conservatively) over a 10 min period I would just need to multiply that value times my product value of $7 Mcf to get the total conservative product loss value, Right? My original post has an attachment which explains the scenerio I'm attempting to model.

 

[dcasto]

since natural gas is valued on a $/mmbtu basis, you need to know the BTU content of the gas. If it's raw unprocesed gas, you will need to know the recoverable NGL content which typically has a higher value than commercial natural gas.

Just more added twists to latexman's comment.

 

[Latexman]

moswitch,

Yes, that is right, as long as the real leak rate event is similar to an orifice-like situation. My point was the real leak rate event may not be characteristic of an orifice-like situation, and you may need more expertise to estimate the product loss than using this simple model in every situation.

Good luck,
Latexman

 

[Latexman]

moswitch,

I did look at your attachment prior to my first post. The sketch on the last page gave me the doubt about your model (orifice) not matching reality.

The sketch (no dimensions) is an open ended pipe of constant diameter. My questions are - what is the length from the source, or a pipe significantly larger in diameter, to the severed end of the line and what is the inside diameter of the line? Is this a specific case or a general model?

Good luck,
Latexman

 

[moswitch]

Latexman @ 16:18 your asking all the right questions but as stated in the attached document the equation is mean to give us a conservitive flowrate.

 

[moswitch]

Latexman @ 16:18 you’re asking all the right questions but as stated in the attached document the equation is meant to give us a conservative flow rate. If I were looking for a more precise leak volume I would have to consider the things you’re mentioning but the current equation does the trick. What I would like to know is how to get from Actual Cubic Feet to Standard Cubic Feet and then express that number in MMBTU?

 

[Latexman]

Okay. See dcasto's post and

P[sub]1[/sub]V[sub]1[/sub]/T[sub]1[/sub] = P[sub]2[/sub]V[sub]2[/sub]/T[sub]2[/sub]

Good luck,
Latexman

 

[moswitch]

I've been away for a couple of days. Thanks for all the help Latexman.