Pumpability of heavy oil

[kirnsi]

Hi,

I have an non-insulated and non-heated tank and want to store heavy oil with API-5 degree, pour 60 F, viscosity 10 CST. How do I determine what temperature is suitable for storing that in this weather. ITs about freezing here and getting low. How low can I let the temperature fall before I start pumping out of that tank.

thank you for your help in advance.

kirnsi

 

[Montemayor]

kirnsi:

How are we supposed to know your pumping limitations if you don't even tell us the the type, model, size, NPSH, etc. of your pump?

As a Chem Eng you know that the viscosity of a liquid determines, to a large degree whether the stuff will flow enough to be pumpable, and that the manufacturer of your pump is who has the information on the pump's pumping limitations.

You should contact your pump's manufacturer or obtain the specifications for the pump in order to determine whether or not the pump will handle the viscosity at the temperatures you will have the oil at. If it can't, then heat it until it get to the viscosity where it will pump.

 

[devaxrayz]

kirnsi:
i would rather not pumping below the oil pour point due to below that temperature the fluid viscosity will raise rapidly and make it harder to pump.
However as Art already said that your pumping temperature will depend on your pump capability (it may able to pump at high visc.)
After you got your pumping temperature, don't forget that your liquid can be more cooled along the piping during pumping. you may need a help of heat tracing.

-rayz-

 

[JimCasey]

You better keep the oil warm. If the oil solidifies at the pour point, you're likely just to suck air. We all have experience with Butter: It comes out of the fridge at a temp colder than the pour point, but heat it up to 30C or so and you have a nice, pumpable, low viscosity liquid. Try to suck cold butter out of a tank and it won't happen.

 

[TD2K]

One client I work with uses 25F to 50F above the pour point as a minimum maintenance temperature for similar reasons. If you are going to let it get down to the pour point, you are looking at some specialized pumps, suction heaters, etc.

At its pour point, it just doesn't move very well. Makes me nervous trying to pump something like that. Now, stuff does get pumped at pretty high viscosity but I don't think you want to get into that area for this service.

 

[kirnsi]

Thanks TD2K and everybody else. that sounds about right. My oil is going into the tank at about 130 F. And we have decided to hold in the tank until it falls to 90F ( Pour + 30F). Hopefully it holds temperature for days.

 

[reena1957]

Dear Kirnsi, I just want (you) to know that
1. You are measuring the temperature near/at the suction line. Otherwise, it might be hot inside the tank but congealed near the periphery and in the suction line.
2. Suction line is steam traced and insulated - otherwise, the internal dia of the pipe might not be same as what you think it is due to again congealed oil at the periphery.
3. The flow in the suction line is mainly by the head available in the tank ( minus the suction created by pump)- Nrmally you cannot expect much help from the pump to push it upto the pump suction, if the suction line dia is already reduced by congealed oil.
4. The tank has a mixer/circulating line to maintain uniform temperature so that you are not misled into believing the temperature is high.
Best wishes

 

[25362]

When you say kin. visc. of the heavy fuel is 10 cSt you should add the temperature at which this viscosity is measured, or even better two or three values at various temperatures, all of them, of course, above the pour point as indicated above.

You may need to adjust the viscosity not only for pumping purposes but for actual burning -atomization, etc.- characteristics.

 

[kirnsi]

Reena,
we are thinking about doing the line wash with diesel first into the tank and then start pumping the heavy oil out of tank.Hopefully that should take care of that. thank you all for the information. It was very helpful.

 

[BigInch]

A diesel wash will may only clean out the line into the tank. Don't see how its going to get any cold oil out of the tank. Hope you're plotting the temperatures.

BigInch-born in the trenches.

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