High Conductivity and NH3 contaminant in steam drum boiler feed water and HP steam

Forums Process & Operational Ammonia High Conductivity and NH3 contaminant in steam drum boiler feed water and HP steam

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  • #43567
    Participant

    We facing a problem that steam drum boiler feed water and HP steam in waste heat boiler ammonia plant conductivity is high, we also anlysis that NH3 contaminant also high.
    Is there anyone have the same issue? and what is the probability source of the contaminant?

    #43923
    Participant

    The conductivity should follow the pH if NH3 is used to control the pH of the drum / feedwater. Your most important parameter of the boiler water is the cation conductivity (after cation exchange resin). If this has increased too, you might have some issues with your (feed)water treatment, and should increase the blowdown. In case of phosphate dosing the relationship of conductivity and pH is probably a bit more complex.

    #43924
    Participant

    Hi,
    One thought is a synloop waste hear boiler (or BFW heater) may be leaking. If so ammonia will be high everywhere in the steam system and places where concentration of H2 can build, such as turbine vacuum condenser inter and aftercoolers, so %LEL can exceed 100%, as well as any heaters using steam where inerts build and eventually temperature of the heated medium falls. If you utilize cation resin cartridges on boiler samples they remove any ammonia so that boiler sample conductivity is reflective of actually anion loading other than OH.

    #43928
    Participant
    quote bedmonds post_id=1566 time=1636454781 user_id=157:

    Hi,
    One thought is a synloop waste hear boiler (or BFW heater) may be leaking. If so ammonia will be high everywhere in the steam system and places where concentration of H2 can build, such as turbine vacuum condenser inter and aftercoolers, so %LEL can exceed 100%, as well as any heaters using steam where inerts build and eventually temperature of the heated medium falls. If you utilize cation resin cartridges on boiler samples they remove any ammonia so that boiler sample conductivity is reflective of actually anion loading other than OH.

    We also expecting that the sources is from that synloop waste heat boiler leakaege, we analyze there is H2 and CH4 content in the after coolers venting. Is that you have an experient regarding of that in your plant ?
    So what can we do to make sure that the reason of this condition is due to the synloop waste heat boiler leakage?

    #43929
    Participant

    Hi, Yes-very similar to my experience for loop WHB leaks. I can’t think of another explanation for H2 and CH4 in steam and NH3 in boilers and condensates. We would run with such leaks for extended periods, but if they get large steam heaters and stripper in an attached urea plant begin to suffer and it is necessary to vent steam from these items to get rid of accumulating inerts. If you can send loop WHB details to bnedmo@hotmail.com I can see if there is any commonality with the WHB issues I’ve seen. In older plants a BFW is used rather than a boiler and they too have had leakage problems. One thing to consider, when operating with a leak, is to make sure water doesn’t back into the loop when steam pressure is higher than loop pressure.

    #43931
    Participant

    Thank you for your explanation.
    If you not mind, what name and where is that plant you operating and how big the capacity of the plant?

    I will send you the data via email as soon as possible.

    #43932
    Participant

    Hi, Re: your questions, location-Canada, Capacity 2100 te/d with nameplate 1500 te/d. This is a plant with boilers. Many years ago, the same issue in a 1000 te/d plant using a BFW heater rather than a boiler. For the 2100 te/d plant primary problem was deposits on bubesheet and under deposit corrosion and eventual large leaks requiring shutdown, while for the BFW heater it was tube/tubesheet leakage that stayed relatively small.

    #43934
    Participant
    quote bedmonds post_id=1578 time=1637839707 user_id=157:

    Hi, Re: your questions, location-Canada, Capacity 2100 te/d with nameplate 1500 te/d. This is a plant with boilers. Many years ago, the same issue in a 1000 te/d plant using a BFW heater rather than a boiler. For the 2100 te/d plant primary problem was deposits on bubesheet and under deposit corrosion and eventual large leaks requiring shutdown, while for the BFW heater it was tube/tubesheet leakage that stayed relatively small.

    Thank you, i will send you the loop steam generation display via e-mail. and we can continue our discussion.

    #44047
    Participant

    Most likely its a leak in the Synthesis loop BFW preheater & your Ammonia converter outlet stream is mixing into High pressure steam circuit. Steam drum integrity would be at risk due to caustic embrittlement (considering Coordinated phosphate base BFW treatment program). There is very less you can do abt as this Ammonia contaminated BFW returns back after turbine condensate treatment. Activated carbon somehow absorbs this Ammonia & further can be stripped-off thru Deaerator vents. For steam turbine, these inerts can easily be vent off by taking hogger ejector set in service but still its that high PH problem of steam drum which may not allow you to linger-on. The worst part would be when you go for the repair as mostly Tube to tube sheet welding affects the Hydrogen service exchangers & the subsequent failure occurs in & around heat affected zone.

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