3 replies to this topic

[alokjaiswal]

Dear Members,

What are the procedures to calculate the boil-off of Ammonia Storage Tank?

I have read that there is a method by which pressure is made to increase inside the isolated Tank and then boil-off is calculated.

I wish to know if there are other methods, then which one is more accurate.

Alok

[kkala]

http://www.cheresour...k-boil-off-rate '> http://www.cheresour...k-boil-off-rate may be useful as an introduction, even referring to LPG/LPG. Same for "BOG-LNG.doc" clarifying the procedure; assuming it same for cryogenic NH3 storage, action may be: accept a BOG (boil off gas) rate in the ball park for basic design (from literature), then let Contractor guarantee applicable BOG rate later.
BOG rate for cryogenic NH3 storage is reported in above reference only once (0.04%), without supporting documents; so it had better be clarified / verified even for preliminary design, by searching relevant sources.
Having quite limited knowledge on NH3 cryogenic storage, I have not heard of specific methods to evaluate BOG rate, which could partially supersede the above. Alok, can you clarify whether method of pressure increase concerns measurement on already constructed tank? What is the status of the relevant NH3 tank?

[latexman]

Calculate the heat transfer between the tank and the environment, Q=UAdT. That is balanced by the boil off rate x heat of vaporization (Q=w.dH_vap). An isothermal operation assumption and summer time environment conditions simplify the worst case design calculation.

[Bobby Strain]

I would consult the tank builder. Most of the low temperature atmospheric tanks I have been involved with usually specify a maximum boil-off rate of .05% per day of the tank capacity.

Edited by Bobby Strain, 25 January 2013 - 04:44 PM.