Storage of crude oil with vapour pressure higher than 11 psia
Storage of crude oil with vapour pressure higher than 11 psia
(OP)
I am currently looking at options for large storage tanks (> 100000 bbls) for hot crude oil. Currently the true vapour pressure is approx 13.5 psia at the storage temperature. The tank designers are of the opinion that above 11 psia, this excludes standard atmospheric or cone roof tanks or floating roof tanks. I have some sympathy with this as in order to maintain temperature at around 65 C, this will require heating which could generate significant amounts of vapour as the heating element of whatever sort (hot oil, water, steam) will probably need to be higher than the bubble point at atmospheric conditions.
So the question is - is the 11 psia vapour limit for standard API 650 tanks valid or can it be raised?
Are there other options? We are looking to raise the bubble point upstream, but need to show that without it the tanks will cost a lot more.
Any insights, experience, links to papers or data would be gratefully accepted.
So the question is - is the 11 psia vapour limit for standard API 650 tanks valid or can it be raised?
Are there other options? We are looking to raise the bubble point upstream, but need to show that without it the tanks will cost a lot more.
Any insights, experience, links to papers or data would be gratefully accepted.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way





RE: Storage of crude oil with vapour pressure higher than 11 psia
RE: Storage of crude oil with vapour pressure higher than 11 psia
So in other words you'd have no big issues in running with a vapour pressure of atmospheric plus the roof weight?
Thanks for reply.
LI
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Storage of crude oil with vapour pressure higher than 11 psia
RE: Storage of crude oil with vapour pressure higher than 11 psia
RE: Storage of crude oil with vapour pressure higher than 11 psia
Obviously it would also not apply if the tank were being built elsewhere than the US.
RE: Storage of crude oil with vapour pressure higher than 11 psia
RE: Storage of crude oil with vapour pressure higher than 11 psia
For other reasons we're trying to get upstream to increase the bubble point, but that's not guaranteed so need to consider all other options.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Storage of crude oil with vapour pressure higher than 11 psia
I think that the last post in this thread is very informative....
API-650 is good to 2.5 psig..... API-620 is good from 2.5 to about 15 psig..
For smaller, more reasonable volumes, a horizontal, saddle supported tank of ASME VIII design should be considered for design pressures of 10-15 psig.
Above 15 psig design pressure, an ASME VIII(or international equivalent)tank must be specified..
RE: Storage of crude oil with vapour pressure higher than 11 psia
Thanks for input - very useful. In your experience is there a practical limit on the size of API 620 tanks? We've been quoted ~ 100 ft (35m) and 100,000 bbls. As we have an awfull lot of crude to store (2MM bbls), if we get restricted to 100,000 bbls it will mean an awful lot of tanks....
Even at 2.5 psig, does it significantly affect the design and max practical size for an API 650 tank?
I know enough about tanks to ask the questions, but not neccasarily to know all the answers, so thanks for you input and if there is any other useful advice out there I would appreciate it for dealing with volatile substances close to their bubble point. I need to maintain 65 C to avoid waxing deposition so can't cool below this without then running into lots of other problems and currently upstream are only giving me crude with a ~70 C boiling point....
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Storage of crude oil with vapour pressure higher than 11 psia
RE: Storage of crude oil with vapour pressure higher than 11 psia
I believe LittleInch is wanting to put a nitrogen gas blanket on the tank (since a floating roof will not be acceptable) to limit losses to evaporation.
LittleInch,
A tank rated for 2.5 psig will likely require a full slab foundation to avoid uplift. At larger diameters, this can become cost prohibitive since the slab thickness will also increase with diameter due to the bending moment. This relates to cylindrical tanks only.
RE: Storage of crude oil with vapour pressure higher than 11 psia
The questions you ask are very important, but exceed my limited tank farm knowledge.
Aside from the issue of uplift and foundation type, anchor bolt style and scheme must be considered.
Also to be considered are the massive foundation loads for these tanks and the costs associated with supporting these loads
Suggest that you contact (and contract with)a storage tank consultant.
Philip E. Meyers literally "wrote the book" on the fine points of storage tank design and tank farm operations.
He works for PEMY Consulting: http://pemyconsulting.com/Home.php
Please respect us....come back to this thread and let us know about your final decisions and why you made them..
RE: Storage of crude oil with vapour pressure higher than 11 psia
I will advise when we complete this aspect, but it may be a few weeks.
IFRs - I understand the pressure aspects, my key question was to try and understand if this 11 psia "limit" was a universally accepted number or not, which has been reasonably well answered and what the possible slaternatives were if a FR tank wasn't seen as accptable, which from an emmissions point of view may well be the case, even though the tank is not in the US.
Thanks again for input.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Storage of crude oil with vapour pressure higher than 11 psia
I believe that DryFoam will work well in the described application very well. If you are interested the guy at Trelleborg is Bob Kelly and he's in their Boston office.
One of the problems with a floating roof that is floating on products near the vapor pressure is the stability of the folating roof. Many have sunk due to localized flashing of the product that causes differential settlement or sinking of one side that allows the underlying liquid to overflow onto the top and flooding it.
RE: Storage of crude oil with vapour pressure higher than 11 psia
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Storage of crude oil with vapour pressure higher than 11 psia
Independent events are seldomly independent.
RE: Storage of crude oil with vapour pressure higher than 11 psia
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way