Purpose of Steam Condensate Stripper on Steam Reboiler

[Pavan Kumar]

Hi All,

I working on the validation of a PSV on a Steam Reboiler( see sketch attached with this message.) There
is a Steam Condensate Stripper(T-8708) installed on one of the vapor nozzles of the reboiler. I wanted to know if anyone can explain the purpose of the Steam Condensate Stripper on reboiler whose purpose is to generate only steam to be used elsewhere. My intent is to understand if any of the overpressure scenarios would be influenced by the Stipper.

Thanks and Regards,
Pavan Kumar

 

[MortenA]

Non condensables (air)?

--- Best regards, Morten Andersen

 

[don1980]

As Morten stated above, this is a deaerator for stripping the dissolved air from the condensate. Over time, even small amounts of dissolved O2 can cause costly damage to a boiler. In the deaerator (stripper) condensate enters at the top and stream enters at the bottom, and the stripped O2 is vented to the atm from a small orifice or valve on the top head (this atm vent is chopped off in your posted image).

Regarding your question about whether this affects the relief design, look at the system and assess all the potential causes of excessive pressure. Ask yourself whether the deaerator pod can generate any pressure. [The answer is no.]

 

[Pavan Kumar]

Hi don1980 and MortenA,

I posted hand sketch of the system with this message that shows the remaining lines of the system. The condensate from condensate flash drum enters the Steam Condensate Stripper at the top while the steam generated from the reboiler enters at the bottom of the stripper. The 1" vent line from the Steam Condensate Stripper is connected to the Steam Condensate header through a flow orifice. If the Stripper is indeed working like a deaerator by removing dissolved O2 then why is the vent line connected to the Steam condensate header?.

Thanks and Regards,
Pavan Kumar

 

[Pavan Kumar]

Hi don1980,

I forgot to show a line from the stripper vent that is connected to the trench( shown now in attached hand sketch.) Is this the vent line that you were talking about?.

Thanks and Regards,
Pavan Kumar

 

[MortenA]

I was just guessing - but does you LP steam consumers all discharge to atm (directly or indirectly)? In this case your O2/non condensables would still discharge instead of circulating in the system?

--- Best regards, Morten Andersen

 

[Pavan Kumar]

Hi MJCronin,

This Steam Reboiler is not attached to a distillation column and I was also confused initially. The re-boiler's purpose is to generate steam from condensate collected in the plant and send it to another process unit. I am not too familiar with this system as I have some limited documents from which I am trying to analyze the system. I tend to think what don1980 is saying is correct just that there is a contradiction that the vent line is connected to the condensate header which I am trying to understand. This Steam Reboiler is installed in one of plants in Texas, USA.

Can you please clarify what you meant by

"or is this some kind of third-world Frankenstein, made from spare parts, poorly functioning and a threat to everyone nearby ?"

Thanks and Regards,
Pavan Kumar

 

[Pavan Kumar]

Hi MortenA,

I think from what I see from the sketch that I have is that the LP steam condensate is sent to the condensate header and not drained out. The steam / non-condensable mixture from the Stripper could be sent to the sewer from the red line I showed in my sketch. I am not sure. My intent in posting this question was have anyone of you seen this kind of system earlier so that I can use the knowledge to complete my PSV validation study.

Thanks and Regards,
Pavan Kumar