Low suction nozzle 1

[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.

 

[Rajender1912]

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.

Thank you for the response!
The flow rate can be adjusted to 200LPM to 1000LPM

 

[Rajender1912]

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

Hi there! Thanks for the tip.
By suction do you mean flow rate? It can be adjusted anywhere from 200-1000LPM

 

[Rajender1912]

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

This is helpful, thank you! Could you please elaborate how did you get to 1.5"?

 

[Rajender1912]

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.

Hello, we have heating coils inside the tank to keep asphalt warm. There is a separate "normal" suction nozzle installed for day to day production, this "low" suction nozzle will only be used during emptying the tank.

 

[Rajender1912]

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.

I agree, unfortunately the tank is old and we are looking to add a low suction nozzle.

 

[LittleInch]

Hello, we have heating coils inside the tank to keep asphalt warm. There is a separate "normal" suction nozzle installed for day to day production, this "low" suction nozzle will only be used during emptying the tank.

Yes, but what is the level of the heating coil above the floor. No point trying to remove anything below the heating coil top surface.

 

[IFRs]

Can you inject a cutting agent to make the mixture flow easily?
In any case your low suction nozzle elevation will be based on the pump used and it's ability to work with viscous materials.

 

[georgeverghese]

https://bituminous.com.au/wp-content/uploads/2015/07/TDS-Cutters-and-Flux-Oil.pdf

https://www.vivaenergy.com.au/ArticleDocuments/936/low-flash-cutter.pdf.aspx

Agreed, one way is to dilute the dregs in the tank with some suitable flux or cutter fluid 3 or 4 times (?), pumping out the diluted fluid each time. This way, you wont have to extend this drain nozzle below the level of the heating coils.

 

[shvet]

This is helpful, thank you! Could you please elaborate how did you get to 1.5"?

(3.14*6"^2/4)/(3.14*6") = 1.5"

 

[LittleInch]

Well it's also area of the open cylinder = pipe area.

So Pi x 2R x h = Pi x R^2

Re arrange H = R/2. R is 3 " so H = 1.5"

Or H = D/4

 

[Rajender1912]

(3.14*6"^2/4)/(3.14*6") = 1.5"

Thank you!