Air in centrifugal pump sucction due to truck tanker unload 2

[villaflora]

Very trick problem with pump

In the company I work for there's a centrifugal pump for pure acetic acid unloading from a truck tanker. The pump data is 60 m3/h x 60m. Since the flowrate is a little bit high, when the tank is almost empty (i.e. when acid level in container has dropped) there's a vortex formation inside the container and air (in fact N2) enters the pump succion pipeline so that it is necessary to prime the pump (remove the N2 from a sample valve at discharge). This operations is very dangerous since the fluid is acetic acid.

Using a priming pump would solve the problem? what would you do in this scenario? Please need a help!

 

[rmw]

I would tell the transportation company that they need to install vortex breakers in the outlet(s) of their trailer's tanks.

rmw

 

[DubMac]

You could put a VFD on the pump to slow it down when the tank nears empty. If you can slow it down enough, should keep it from vortexing.

Another idea would be to go to another type pump; as this service is not well suited for a centrifugal. I would suggest a little gear pump (Viking, Roper, etc.), or a progressive cavity, or even a diaphragm pump. These positive displacement pumps are most commonly used for tanker unloading.

If you can't get enough volume from a PD pump, you could leave the centrifugal and add a PD pump to do the tank stripping at the end.

 

[MJCronin]

Dubmac has the right solution....

A small PD pump in parallel with your existing pump sounds about right.

But, it also sounds like this truck was not set up for bulk deliveries of acid and you are making your facility adapt to the shorcomings of the truck. Most bulk chemical deliveries I am aware of use either a pressurized truck or a small pump on the truck.

Was the truck intended for this kind of service ?