from hydraulic design to thermodynamic pipelines

[IngExp]

Good evening to all,
I am an engineer with knowledge from the university of plumbing concerning free and pressured pipes, free sleeping channels and all that concerns rhinestones, turbulent motion, laminating etc.
If I wanted to recycle in thermodynamic design regarding pressure pipes of oil&gas plants what should I add to my current knowledge to do so?
I see that we always talk about laminar motion, turbulent and similar, with the obvious addition of temperature and gas...

thanks to all

 

[paulpaul]

the study of the motion of a gas in the pipelines can be done at different levels of deepening, depending on the applications: can be used incomprehensible fluid approach for low speeds or for a first sizing. laws are equal to those of hydraulics, obviously taking into account the properties of gas (often treated with mixtures), which are to be calculated with dedicated state equations (density) and appropriate correlations for the necessary transport properties (viscosity). for the determination of the friction coefficient you can use the typical correlations of hydraulics or the digitized moody diagram, available in any text of hydraulic/fluidodynamics. find also a commercial sw plethora, for example the excellent and economic sf pressure drop.

moving to a higher plane, when the speed is high (safety valve discharges, for example, but also certain travasions between tanks with high expansion ratio or turbomachine ducts), an approach based on the compressible fluid is necessary, and therefore it is necessary to pull within the number of machs and shock waves: in case of absence thermal exchanges, the fundamental problem of determining load losses is known as "flow of the make", and you can find it on every book of gasdynamics (e.g. "fundamentals of gasdynamics", zucker, wiley) as well as online. It is obviously a very laborious method to implement on pc, but you find commercial sw here too.

I believe that with pressure drop you can solve 90% of oil & gas problems: the only limitation is the non-management of mixtures, quite limiting (perhaps they solved the problem).
otherwise you could use very sophisticated process simulators (and expensive), such as as aspen hysys, world reference.

Hi.

 

[IngExp]

ok thanks! while if I were to study phenomena of fatigue due to temperature variations? do you know any good document/book?

 

[paulpaul]

the rules on process piping (asme b31.3 and en 13480) also treat this aspect. What application are you talking about? for my experienticity, variations up to 150 °C do not constitute a problem for fatigue if the tube is “sufficiently flexible”, but it is necessary to evaluate in the specific conditions and geometries. on the other hand, pressure pulsations and vibrations are critical.

 

[IngExp]

Let's talk about temperature that also reaches 500 degrees! for pressure fluctuation I studied wholer curves and goodman smith diagrams, but for the temperature I am trying to figure out how to do... I can also have tanks in addition to piping, for that I ask. .

 

[paulpaul]

with those temperatures you normally use expansion compensators, and the standards give the admissible according to the material for various temperatures, and normally you just need static verification. for vibrations and pressure pulses serve much more specialist studies.
in any case the rules I mentioned suggest to you when and how to assess fatigue: other standards dedicated to specific applications can provide additional criteria.
but you started asking questions about the fluid dynamics of gases and then answer questions about the construction. . .they are two very different topics even if always tied to piping! I suggest to proceed by degrees.