Baffle on a new tank

[DaniMP]

Hello everybody !

I am designing a new oily water tank, and I want to have a compartment with a baffle so that the oil at the surface can flow from the main compartment (the tank) to the oil compartment.

Are there any norm / constraint that I need to know ?
For example, I have uploaded some very simple drawing regardin the shape of the compartment, which should I use, etc...?

http://files.engineering.com/getfil...-4d88-bec8-e8ecdea32d5d&file=Storage_tank.jpg

Thank you for your help !
Daniel

 

[DaniMP]

I have looked at API 620 / 650, and I don't tjink they ever talk about this kind of issues ?
Thank you again !

 

[fegenbush]

The baffle designs that you have in your attachment are not ideal. The problem with flat plate baffles is the possibility of pressure on one side of the baffle only. Flat plates do not handle this condition well. Sealing the baffle plate against the floor plate is also treacherous due to the possibility of tearing the floor plate.

Please reference your previous topic for an oil skimmer which is a common tank accessory.

 

[IFRs]

API 620/650 have nothing for you for this.
A plain or saw-tooth weir box sounds like what you need.
To design it you need to know the process and operational conditions.

 

[DaniMP]

Thank you fegenbush !

I'm not sure I can have an oil skimmer as my oil is very paraffinic and I would fear to have the skimmer stucked on its pole if my heat control (heat coil) does not work well / it is too high for the coil...

IFRs : what is a saw-tooth weir box ?

Thank you !

 

[IFRs]

A stationary weir box works if your water/oil interface is always at the same level and you simply need to allow the oil to fall into a box whose low side is at or just above the water/oil interface elevation. The saw-tooth profile on the vertical edge of the weir is an attempt to minimize the water flowing into the box.

 

[DaniMP]

Thanks !
Unfortunately, my level won't be constant in the tank.But of course I could design a weir box and when my operator want to remove the oil phase, he will artifically raise the level in the tank.

So there would be no solution with a baffle if I reinforce it or else ? My constraint is mainly that with this design, it would be very easy for the operator to use it : if there is a level in the baffle compartment, he can just open a valve and let the volume purge in the system, like once a week / month.

 

[fegenbush]

In your attached picture, top option C with bottom option B is a weir. The height of the weir box should be small (2 ft might be a good starting point). This limits the maximum amount of head pressure that the weir will see.

If you need help on designing the weir, a good reference is Water Resources Engineering by Linsley and Franzini. My copy is copyrighted 1964, so you would have to look on the used marked to find it likely.

 

[dhengr]

DaniMP:
What would happen if the weir box floated? It is guided and controlled laterally, but can move up and down with the liquid level. It has a bottom and four toothed sides, maybe a bottom and cylindrical toothed side. Its bottom has a drain and flexible hose to allow vert. movement, but it also has four legs to stop it 2' short of the main tank bottom, so as not to crush the drain hose. It also has a heating element right on the weir sides and bottom to improve/assure flow in and around the weir box. In fact, this heating element goes right up the drain hose. Rube Goldberg is still alive.

 

[DaniMP]

Thank you dhengr !