liquid water carryover in natural gas

[rotw]

Hi,

Can someone indicate a formula to calculate the quantity of liquid water carry over in a natural gas stream (hydrocarbon gas), knowing the gas composition, actual pressure and temperature ?
It can be also a formula which is function of the relative humidity ?

any indication please ?

Thank you
regards

 

[zdas04]

Water is the most prevalent fluid on the planet. It has been studied more than any other fluid. Hydrocarbon phase change is just as complex as water phase change. Yeah, you have to deal with at least as much complexity and even more uncertainty.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"

 

[rotw]

ok so all in all, if you add up all these combinations of water condensation, (eventually hydrates), gas condensate... then it becomes quite a mess going on there.
I was used to use simplistic approach in the past, this is just an example that things are learned to be unlearned, as I discover how complex the problem are in reality, especially with regard to what Zdas mentionned about 4 bar and 1% CO2/H2S in a mixture being sort of threshold.

 

[zdas04]

As Engineers we often lose track of the concept of "good enough". I can design equipment and systems with enough excess capacity (whatever that means, it is different for every component) to be able to work effectively over most of the required operating range and to fail gracefully for the rest. I design compressors with the design point less than 70% of max available horsepower. I design gas/liquid separators with velocities about 1/2 of max velocity using traditional sizing. I never approach a boundary condition with my design. I have more successes than failures. If I insisted on less "brute force" and more "elegant solutions" then I would be very disappointed when Mother Nature hit me with the systems equivalent of a "100 year flood". I do this by never using code to do what I can do with local-sensing controls, avoiding delicate instruments, minimizing things that use control gas, etc. My projects are not elegant, but they are robust because I admit that multi-phase flow is too fraught with uncertainty and has too much innate randomness for elegant solutions that operate close to a performance envelope.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"

 

[rotw]

Zdas,

I really like and adhere to your approach.

This also remind a course I have attended long time ago on numerical methods. The Teacher was a master of computational methods.
But because he was a real engineer instead of a mathematician, although mastering the subject of numerical methods, he always told us to avoid using numerical methods when possible. What to use instead ? try to use basic equations, to define order of magnitude first.
Have a physical understanding of what is going there by defining the amplitude of the variables (velocities, pressures, concentrations etc.) by use of simple (analytical) methods. When you build that physical screening then "maybe" move ahead with numerical methods but with great care (avoid if possible to deal fluid dynamics problems). He also used to tell us that validation of numerical results is not via comparison with experiments, but it has to be mathematical, indeed by bounding the results with upper/lower limits for instance using the order of magnitude philosophy mentioned before.

I really liked this teacher and the caution and the serious in dealing with problems of mother nature.
That is why I say back to the liquid carry over topic, it was good to know about how things deviate from theoretical models.
It is also good to know which application requires accuracy and good confidence and on which one it suffices to have some sort of estimates.