Atmospheric tank with high design temperature

[ChriChri81]

Goodmorning at all,

i have a question about atmospheric tank: i need to know your opinion about the design of a tank that has a design temperature of 350°C. We know that the maximum design temperature provided by API 650 is 260°C using appendix M. What about higher design temperature?

Is it possible to design a tank with design temperature of 350°C using API 650? If not, what is your suggestions?

Thank you in advance!

Chri

 

[JStephen]

You can design it and build it, it just won't fall within the scope of API-650. It would probably help to have someone familiar with the problems of heated tanks involved in the design.

ASME B&PV Code includes allowable stresses for those and higher temperatures, but doesn't cover any of the specifics of atmospheric tank design.

 

[metengr]

Are you sure this is just a storage tank and not a pressure vessel?

 

[MJCronin]

CriCri...

I agree with meteengr..... I smell "pressure vessel"

What is the vapor pressure of the liquid at 350C..??

What is the liquid..??

As we begin this traditional slow and painful "question and answer segment" to the thread, will we find out that this is the first tank you have ever "designed" (specified) ?

-MJC

 

[unclesyd]

They are molten salt mixtures stored at these temperatures.

We store molten salt at around 600F+ in what we call a day tank to trim our salt heated reactors. This is a process where the reaction is exothermic and the molten salt is a coolant. I can't recall the exact temperature of the salt but we use it to generate 650 # steam with some superheat.

We also have the tails off two distillation columns that store organics at around 430F. These material are high boilers in respect to HMD (Hexamethylene Diamine} which boils around 400F. These tanks operate at 8" water with N2 conservation vents. All other tanks in this tank farm are designed to API 620.

We also store Therminol VP-1 condensate at around 500F. This tank is also nitrogen blanketed. There is a low pressure relief valve on the tank. I don't recall the set pressure is but it is quite low. It is installed because there is a very,very remote possibility that condensate form a vapor system operating at around 10 psig gauge could get to the tank and flash at around 600F.

I am try to get in contact with someone I know who can access the data for these tanks.

 

[ChriChri81]

Yes,
Metengr is a tank,
MJCronin the liquid contained inside of this is DIATERMIC OIL TERMINOL 066; now i will inform myself about vapour pressure of the liquid @ 350 °C.

 

[NickDubya]

Vapour pressure of T66 at 349 °C is 12.2 psia. It would be unusual to keep this in a vented tank at 350 °C as the fluid would rapidly oxidise. We manufacture Thermal Fluid (Diathermic Oil) Heaters and design systems and wouldn't let fluid get that hot in a vented tank, we would use a thermal buffer between the main thermal fluid system and the expansion tank, the tank wouldn't get much above 60 °C. VP1 is used in vapour systems and needs to be pressurised with the nitrogen blanket to keep it liquid in the expansion vessel under normal operation. With low vapour pressure fluids, the expansion and contraction of fluid in the system needs to be balanced by bleeding the nitrogen blanket/vapour mix and re-pressurising as the level rises and falls in the expansion vessel. Nitrogen is used to prevent oxidation. Light fractions are typically removed via a deaerator to the expansion tank and vented with the nitrogen as the level rises and falls.