9 replies to this topic

[Pronab]

Amine is carry over through PV-A valve to downstream Low Pressure fuel gas KOD from the Rich amine Flash Drum. Top of the Flash Drum having a packing section (Rasching ring) followed by demister pad. My question is there any other possibilities to carry over unless there is a channeling through the packing? Please refer the drawing.

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[Zauberberg]

Try increasing the flash drum pressure to e.g. 8-10 barg. This will somewhat reduce gas velocity through the packing and possibly point the investigation further in a specific direction.

 

Try reducing the amine flow on top of the packing and see if this helps. If it does not, the culprit is probably excessive gas velocity through the vertical section (i.e. excessive gas flow - look for causes upstream). If it does help, you may have partially clogged packing.

 

Get the Instrument technician check the level transmitter(s). You could also have high liquid level inside the drum, yet not captured by the level instrument. High level may promote flooding.

 

If this is a problem from day No.1, you'll just have to live with it because that's how it was designed in the first place.

[Pronab]

Lots of exercise has been done so far to point out the carry-over. Top amine flow reduce however not sure still carry-over. Level transmeters are working fine and there are other transmiters which are responding, all of them can't went faulty together. The loss is through the Top section it is sure and LP fuel gas KOD level build which was unusal. This is not the day no#1 senarion, at normal condition KOD level not increase. Only top section pressure not try to  increase. My most interest is to figure out whether there is any channeling/ posibility of channeling from the TOP packing section which might be the culprit to carry over.

Thanks for your time.

[Zauberberg]

All things equal, if now you are starting to experience problems it's either the flash gas side (i.e. more flow), the amine side (i.e. more flow, or high liquid level), or the packing itself (upset, or dirty/clogged).

 

Amount of flash gas you could track by plotting the trend of % controller output for the overhead PCV. The same for amine side control valve.

 

Ultimately you could try to perform a pressure survey with a single digital gauge, around the packing (i.e. could be the top connection of the level bridle and some convenient point in the overhead system). The bad thing is that you probably don't know the "normal" parameters (when everything worked OK), so there is nothing to compare the results with.

[Pronab]

It is clear that amine is carry over from the Flash drum top packing section. Is there any device/technology to confirm whether the Packing bed and/or demister pad is blocked or channeling or not?

Thanks in advance.

[Zauberberg]

You can do gamma scans. Check companies like Tracerco etc.

[Pilesar]

Demister pads can be damaged and have open gaps in them. Failure of the packing section support might also show these symptoms. Gamma scan is the next step unless you open the flash drum to look around. I would check the data historian for unusual events that might have surged the flash drum to precipitate the problem.

[gegio1960]

what about foaming?

https://www.cheresou...ine-flash-drum/

good luck!

[breizh]

Hi ,

I believe that you need a reference  to interpret a scan , I refer to previous experimentation on a distillation column where trays were damaged . Zauberberg is certainly right .

 

Breizh

Edited by breizh, 04 May 2017 - 01:34 AM.

[Pronab]

Foaming is not happening in our system. Our previous experience was foaming in the Amine Absorber column only, not in Flash drum or Regenerator. We try to increase feed but same phenomenon happen, carry over from flash drum to down stream fuel gas KOD. Now unit is running at low feed.

Thank you for your time and interest.