RG Boiler

[SRIVASTAVA PRABHAT]

Hi, Friends
I want your wise view regarding RG boiler, Here I am in Ammonia plant Topsoe design capacity of 2000MTPD. In plant common steam super heater with RG boiler. Few days before we observe sudden decline of process gas temperature and steam temperature also increase in Secondary reformer DP. With calculation and water balance we believe that there is minor leak, we still keep plant running monitoring downstream parameters.
After a week we found that all process parameter revert back and get to normalized. I could not understand the reason? if there is leak then how it can stop suddenly? If there is no leak then what could be the reason for pressure drop and increase of DP.
If any one also have such types of experience please share.
Regards
Prabhat

[Edmondson Bob]

Hi Srivastav,
A few questions:
location of secondary dP taps-is the low side downstream of the superheater?
Details of boiler bypass internal tube damper or plug-could it have gone closed?
Is process condensate flow monitored and if so did it go up when the incident occurred?
We have had experience with damper movement, with large boiler leaks and superheater leaks and on the surface this sounds like a dmaper issue
In modern plants metal dusting of components so it should not be an issue for you-but in the past lead to damper and liner failures

[SRIVASTAVA PRABHAT]

Hi, Frined,
Actually This RG Boiler have Two boiler along with steam super heater. First boiler is E-206A, second boiler is E-206B. Gas coming from E-206A going to steam super heater after than partial cold gas goes to second boiler E-206B.
Your first answer is : Yes, secondary reformer measure from Reformer cold collector gas ( HP tapping) and LP tapping is outlet of second RG boiler.
If you share your mail id, I can share detail with operational parameter and with sketch.
Actually I have done detail study with drawing, and thermocouple location and past article, but not able to conclude.

[Edmondson Bob]

Hi Srivastav,
Thanks for the clarification. My e-mail is bnedmo@hotmail.com if you would like to forward the details you mentioned.

Best Regards, Bob

[yoruk giray]

Hi Srivastav, I have faced some problems like you but, our designer is Kellogg. I would like to scrutinize your problem. Can you share your problem details? my mail is girayrk@hotmail.com.

[Satyajit Mahapatra]

Hi Prabhat,
It is quite interesting. As Bob already said that it is most likely the RG boiler short bypass valve (damper) malfunction issue. If you can share your P&ID for the RG boiler and DCS snapshots from Mixed point to HTS, trending of Mixed point pressure, we can review and give you the feedback.
I believe that your upstream pressure definitely increased and plant load reduced during the incident.
The lesson learnt from this incident is that do we know what caused this incident, what actions should have been taken during the incident, what are the process safety risks and the consequences. If you can analyze in advance, you can prevent any further damage to the plant.
Kind regards,
Satyajit

Satyajit

[SRIVASTAVA PRABHAT]

Dear Friends,
Please provide your time, I can plan a meeting in MS team, where I will explain in detail of our observation and action taken till date, P&ID and DCS graphic with tags no

[Edmondson Bob]

Hi,
Any time can work for me. I am a rookie with the use of TEAMS but do have it can try to join.

Best Regards,
Bob

[Tandon Shashank]

If RG boiler tube in running ammonia plant leaks then what can be its adverse effect to downstream HT catalyst.

[Edmondson Bob]

Hi, Operation with RG boiler leaks is often done and with all volatile boiler treatment the HTS dos well. With coordinated phosphate treatment there may be issue but I have no experience. There will be refractory damage and dryout of repairs, if Repairs to the leaking tube are not easy since PWHT ne follows vendors curves is very time consuming and use of Thermbond high alumina/low silica product saves a lot of time. Lab testing showed that the vendor time can be cut by a factor of three but time a reluctant to take on any risk. Repair (plugging) of the leaking tube is difficult with PWHT difficult and 1/2 bead methods don’t always produce a good result. I am assuming you refer to firetube boilers. For most water tube boilers a spare bundle is installed with is easier and faster. Hopefully others will respond with their experiences.

[Tandon Shashank]

Hi BOB. Thank you for your valuable reply. Also please educate on what can be its adverse effect to downstream HT catalyst.

[Edmondson Bob]

Hi Tandon, I can’t be very helpful-I’ve not seen any damage with operation for extended timesd with leakage with all volatile boiler treatment. I have seen dP buildup with sodium zeolite treatment due to deposition of NaCl in a very old plant. Of course that is with many hundreds of ppm of Na salts in the boilerwater and with only a few ppm of phosphate I imagine eventually there would be some dP increase but I imagine it would be very slow.

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