Fuel Oil Pumping form a vessel

[lukin1977]

Hello
We have to fully unload a vessel containing 2000m3 of fuel oil. To do this we use a 60m3/h vane pump installed on the docks platform
The unloading process is done ok until the las 0,5m deep of fuel oil. The pump does not suck anymore because the remainig fuel oil is too "thick"

What can we do to pump out from the vessel the remaining fuel oil?

Regards

lukin1977

 

[Ripz]

Are you sure your suction piping is submerged to the base? Usually, suction piping has a clearance from teh base.

You can try a positive displacement pump, eg diaphragm pump.

 

[lukin1977]

Ripz
Yes. I am sure the suction pipe is submerged to the base. On very warm days the vessel is fully unloaded because the fuel oil is "thinner"

 

[LittleInch]

You might have anyone of a host of problems here. One - what is the vertical distance from the pump inlet line to the bottom of the hold? If the density rises too much you might run out of vapour pressure and be creating a vacuum at the pump inlet.

What is the configuration and size at the bottom of the pipe - It could easily be you're sucking in air by vortexing. Consider enlarging the pipe at the bottom and introducing vanes on the outside to prevent swirl.

To be a bit pedantic, pumps don't suck. The fluid is driven in atmospheric pressure when you create a lower pressure downstream. I realise most people thing of this as "sucking", but it is not correct terminology.

A submersible pump would probably be better to avoid all these issues.

By the way- does it take 33 hours to offload your vessel?? Seems a very long time to me.


My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[lukin1977]

LittleInch

yes. It usually takes 33 hours and more!
The vertical distance asked is 5m aprox
I have already searched for a submergible pump for fuel oil but could not found one yet. Still looking

 

[Compositepro]

If it is too thick to pump then the only answer is to thin it. It is likely that the coldest oil is is on the bottom because it is denser and it is in contact with cold water on the other side of the hull. You could recirculate some oil through a heater to warm the residue in the vessel.

 

[miningman]

I would have to think that there is a lot more than 0.5 metres of ships hull submerged in the water. I therefore suspect that the temperature of the material being pumped is a red herring. I suspect that Littleinche's suggestions could get to the root of your problem, and I say this having successfully emptied ships hulls of diesel fuel about 1000km north of the Arctic Circle. When you say it is fuel oil you are dealing with , do you mean diesel fuel or Bunker C , or something else.

If it is Bunker C , then yes perhaps viscosity is a legitimate consideration. If it is diesel fuel, throw in an air powered Wilden or equivalent. Yes all the rubber components will be toast and the end of the exercise but you get all the benefits of a submersible without having to deal with explosion proof motors , or confined space entry etc etc.

 

[BigInch]

Mix some diesel in with it.

I hate Windowz 8!!!!

 

[lukin1977]

I will get more information about what kind of fuel oil it is.
The F.O. is used to feed the furnace of a cement factory. The fuel oil is pumped from the vessel to the furnace tank which is about 700 m from the vessel and at 15 m height.

Suction pipe: 6"
Outlet pipe: 6" and after 30m it is increased to 10"

 

[BigInch]

And the temperature of the oil please. Can be very important with fuel oils. Actually it would be quite easy for a heavier fuel oil to need more than 15 m to flow 700 m before one of us dies.

Or just solve the problem with the diesel mix. Your cement probably won't care a bit if it was heated with fuel oil, or fuel oil and a little bit of diesel.

I hate Windowz 8!!!!

 

[LittleInch]

Can you give us details of your pump please - pump curve, type, model, power etc. Also looking back on this when you say it doesn't "suck" anymore, what exactly happens? Does the pump start making strange noises and flow reduces or does the pump trip or just stop flowing?

What is the arrangement at the bottom of your pipe in the tank? - sketch it and post it - it will help a lot.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[lukin1977]

I will get all the data asked

I have some pics

 

[lukin1977]

This is the Pump

 

[lukin1977]

Another pic

 

[lukin1977]

Picture of pumping station