Low suction nozzle

[Rajender1912]

Hi All,

I am designing a low suction nozzle for asphalt storage tank. The sole purpose of the nozzle is to help taking as much material out of tank as possible during emptying/cleaning of tank floors.

Outside of the tank is just a usual 6" nozzle, but inside, the idea is to install an elbow down with a pipe spool extending down as close to the tank floor as possible to take more material out. This nozzle will never be used while normal operation, only while emptying the tank.


That being said, I wanted to ask how can I determine how close to the tank floor I can safely be, to clean out as much material as possible and also not affecting the pump attached to nozzle?
Attached a quick sketch for reference.

Any guidance will be much appreciated!

 

[LittleInch]

Do you have a flow rate?

I would aim for a velocity of 0.3 to 0.5 m/ sec coming into the circumference of the cylinder from the end if the pipe to the floor.

You could gave room here to have reducer and double the diameter of your line to further reduce the inlet velocity into this area.

 

[EdStainless]

How much suction do you have?
A larger pipe inside and a bell mouth entrance would help.

 

[pierreick]

Hi,
Probably the day you want to use this nozzle it will be plugged.
To me it should be a straight pipe within the tank to mitigate the risk above.
My 2 cents
Pierre

 

[shvet]

the common industry practice is 0.3-0.5 D
2"-3" in your case

for intermittent service many users practice
the area of the free flow cylinder underneath the pipe = the area of pipe bore
1.5'' in your case

 

[Trestala]

Internal pipe should be elevated by half of the pipe size. In your case it is 3".
If you really want to take as much material as possible, you can just slope the tank floor and add a sump on the lower end.

 

[LittleInch]

I have also seen a smaller, sometimes flexible tube laid within the larger pipe to slowly strip the remaining gunk off the floor using a PD type pump which doesn't mind gulping air / vapour.

If this is asphalt though how are you keeping it warm? You don't want to go below the level of heating coils or even expose them as they then coke up or overheat.

You need to look at the bigger picture here when you're dealing with asphalt.

 

[Snickster]

If this is a new tank you might want to install a sump arrangement or a true low nozzle which is all the way at the bottom of the shell. What good is it to leave a few inches of asphalt in the tank for cleaning and inspection.

 

[LittleInch]

Unless you can actually heat the floor the asphalt goes solid or viscous enough that it doesn't flow.

So it's easier to just dig it out sometimes.

Horrible job though.