Little inch,
it is very clear ! this is a LL separator.
bottom valve is closed , open only to drain the separator.
Green is light phase , red is heavy phase .
The interface is controlled by the height of the inverse U pipe .
Pierre
Disconnect from light liquid (green) and connect to vapor space (white). The same as for G-L level control? Am I correct?
What if the horizontal run of U-pipe will be oversized so velocity is almost 0? Will it help to avoid carryover?
Little inch,
it is very clear ! this is a LL separator.
bottom valve is closed , open only to drain the separator.
Green is light phase , red is heavy phase .
The interface is controlled by the height of the inverse U pipe .
Pierre
Shvet.
Block the light line, no connection to the vapor space.
Only heavy phase going through the inverse u pipe. Of course the valve is closed.
Little lunch,
When liquid at rest, nothing special. the phase will separate.
Pierre
If U-pipe is not connected to the separator then U-pipe elevation will have nothing to deal with L-L interface in the vessel. Am I correct?
The highest point of U-pipe can be 1 meter higher or 1 meter lower and this won't affect L-L level. Or I do not catch something?
@LittleInch
This is the classical continious 3-phase separator for chem industry. The difference (for me personally) is the weird methods to control L-L level. I have not met such U-pipe for L-L application and the contractor denies to provide a detailed comment.
The U-bend will not act as a Wier. It will act as a siphon. Even if it acted as a wier, it would not control interface level. It would behave the same as the other wier, controlling liquid level.
A description and explanation are given in Perry's chemical Engineer's handbook - page 15-26 -7th edition
To prevent siphoning effect the upper part of the inverse U should be connected to the vapor space/vent. No connection between the Inverse U leg and the light phase.
Pierre
Thank you very much, Pierre. That is exactly what I need.
for info, not for reply
Actually my concerns are related to LL densities. Densities difference is small ~20 kg/m3 or 2% and those are variable/unstable. I would not post such issue if this was similar to a hydrocarbon-water separator.
Definitely the low difference of density is a key parameter together with the height of the heavy drain leg. A sensibility analysis of those parameters has to be done.
Instead of using a fixed head ZH, I would advise to install an adjustable leg. This is my experience with mixer settlers for the separation of rare earth (10 years).
To answer to George, for emulsion, the keys parameters are the residence time, the ratio Heavy to light materials, the viscosity of the phases (temperature). Coalescers of different types and materials will help the separation.
Note: Your separator must be equipped with sight glasses for operators to visualize the position of the interface.
If your phases have different conductivities, an online analyzer is going to help.
Good luck
Pierre
At liquid levels shown the pressure at the upper tee connection is basically equal to the height of the light liquid. This height of the light liquid produces a differential pressure of the light liquid relative to the tee connection. Looking at the heavy liquid there is really no differential pressure between the bottom-most level of the heavy liquid and the center of the tee since the static height down equals the static height going back up so the heavy liquid is in equilibrium and can only flow at the tee and out by weir type flow. Therefore the light fluid will preferentially flow due to the differential head while the heavy fluid will only flow due to the pressure drop in the tee due to the flow of the light fluid. Therefore the light fluid will preferentially empty out of the tank through the tee and not over the main weir.
