Store Hot Naphtha into Ext. Floating Roof Tank 2

[mnfsbss3]

All,

What should I do for my storage tank (external floating roof type, which Working Press. is atm) if I will store hot naphtha(max. 50degC) at least 10 days without product cooler? Is the increment of RVP of hot naphtha will affect the tank?

 

[Jason5000]

A floating roof tank will only handle liquids with a TVP up to a certain point, where TVP is a function of RVP and temperature. I believe there are some nomagraphs in the GPSA handbook with these relationships. At a certain point the tank seals will begin to leak; the TVP of material stored in the tank may be an environmental requirement/limit depending on where you're at. If your TVP gets way too high you can even form a gas bubble under the roof and potentially sink the roof. I'm by no means a tank expert, but I believe the limit I've heard before is about 12 psi TVP to a typical floating roof tank.

 

[IFRs]

As long as the liquid is not boiling ( ie vapor pressure greater than atmospheric ) the EFR will not be damaged. At pressures above certain limits, the EPA in the USA will not sanction the use of a floating roof because it does a poor job. Check your local regulations, or NSPS / 40CFR60 Kb in the USA.

 

[chemicalengineerthai]

in case you can not avoid,

1) low pressure/ATM API tank can operate 14 psi RVP if higher than this other type of tank shall appy. Please run the plant abit lower pressure/higher bottom temp than usual to improve lower RVP of product,. release more gas from distillation, RVP will improve but a bit flare loss

2) It will loss vaporize but not mean tank will damage since the liquid is from distillation column at bubble point and cool down by bare piping along from plant to tank, eventhough it has not enough cooling, 50 C still not so hot.
3) Breathing system of the floating roof already design for it.

4) Do not fill liquid higher than 70% of the tank during this period

5) run tank farm pump circulate time by time to gain cooling around network piping