Storage temperature for crude oil and other questions

[fracontr]

Hello:

I am a young process engineer. I need mix into the tank 2 crude oils, and i must design an aboveground storage tank for a final crude oil (35ºAPI), networking capacity for determining, normal ambient temperature 11ºC and min temperature -15ºC , max temperature 28. Wind 180 km/h, sismic zone 2B-UBC.

I have a few questions about this:

-Exist references to determine the suitable time of residence or some recommended minimum?

-Which is the recommended temperature of storage, how many degrees above the pour point would be recommended to store the crude oil?

-What criteria are used to determine the non-working capacity (volume below the bottom invert of the outlet nozzle)?

-Which is the recommended time of agitation to reach a homogenous mixture?

Thanks in advance.

 

[jmw]

Any reason for the above ground storage? Why not blend on demand to the user? Online measurement instrumentation exists for degAPI or viscosity. Density transducers such as manufactured by SolartronMobrey or Peek (two of the industry standard instruments) provide degrees API online and in real time. Other technologies such as some "coriolis" density meters (mass meters used as densitometers) may also provide the necessary calculations. Jiskoot (

http://www.jiskoot.com)

provide jet mixers which will provide effective homogenisation, and blenders as a package to provide the complete blending solution. Storage may provide problems; if the crudes are incompatible then they will tend to separate so you will need to mix in the tank. On the other hand, if you inline blend then the product delivered is homogenised by the blender and the product is no different as the user receives it.
The other main reason for storage tanks is for test and correction. In the belnding of heavy fuel oils, even using process capillary viscometers, the fuels are blended into storage where top, middle and bottom samples are taken for lab analysis and for corrective action (adding further quantities of one of the components). This is usually because of the problem of obtaining accurae on-line measurement but new viscosity technology now overcomes this and allows inline blending without the need for the intermediate storage tank... fuel is blended straight into the loading facility. Measurement is not a problem for degrees API as the technology has existed for 40 years or more (magic figure, 40!)
In the oil fields it is necessary to have strict controls on the allowable density and viscosity of the crudes at the pipe line temperature. Where heavry crudes are involved it is not unusal to blend with distillate using on-line density and viscosity measurements.
Sorry, i can't help with the other questions.
If you would like more help with online measurements, post again.

 

[fracontr]

jmw:

Many thanks for your aid, i wasn't think in line blend because the client dont want that.
He need a AST! why? i'm not completelly sure.

Any ideas about where i can found the answer to the other questions?

Many thxs again!

 

[jmw]

The best i can suggest is to try the ASTM and API web pages for design standards.