4 replies to this topic

[Mech.Engineer]

In Vapor Space, How varies its percentage with pressure and temperature into the vessel ?.

Is it possible calculate this amount of steam produced internally ...?

In advance...Many thanks...!

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[Art Montemayor]

Mechanical:

There is no hard and fast rule or regulation regarding the minimum vapor space requirements in LPG vessels. I believe that is what you intend to ask in your query. Usually, the amount of vapor space dedicated to an LPG storage or transport vessel is dictated by corporate standards since there are some inherent risks involved in allowing for too little internal expansion in such vessels. I usually design for 85% of the total vessel to be dedicated to saturated liquid payload. I have gone as high as 90% on some specific tank and process designs – but I would not recommend going any higher in total, maximum saturated liquid content.

There is NO STEAM PRODUCED in LPG storage vessels. I believe you mean to state “vapor” and not “steam”. The saturated vapor generated inside a storage LPG vessel is dependent on the heat leak allowed through the vessel walls. To the degree that you can shade, insulate, or protect the vessel from the local weather and summer time temperatures, you will generate saturated vapor inside the vessel and its saturated pressure will increase proportionately. You can calculate the expected heat leak and, as a result, also the amount of generated saturated vapor.

[MrShorty]

Yes it is possible to calculate the amount of vapor in a closed vessel, but temperature/pressure are of minor importance in the calculation for a pure compound. Gibb's phase rule for a one component - two phase system shows that there is only one degree of freedom. This means that, at a given temperature the pressure will be fixed at the saturation value regardless of the amount of vapor or liquid present. The most important quantity in calculating % vaporized will be the total amount of propane in the vessel. A flash calculation is necessarily an iterative calculation, but you calculate the volume occupied by the liquid, which allows you to determine the volume occupied by the vapor, then, from the densities of the two phases, you can determine the amount of material in each phase.

[Mech.Engineer]

Thank you Art..

I knew that about difference between Vapor & Steam...It was just a mistake, but thanks for correcting.

I WOULD LIKE TO ASK YOU SOMETHING ART:

Don`t you have a website or reference document about friction losses calculations in pipelines when LPG or PURE PROPANE ARE FLOWING through them.

[shan]

Friction losses of fluid through pipes are merely related to fluid velocity. There is nothing special for LPG or C3.