3 replies to this topic

[Chandra S]

Hi all,

I'm Chandra working as a process engineer for past 8 years in a refinery. Currently I'm leading a task force to resolve one of the major issue in our plant, corrosion at Condensate Fractionation Unit (CFU).

Background:
- Unit commisioned in year 2000 using sweet condensate as feedstock; same feedstock till today.
- Additional feed stream is wild LPG from Platformer unit to stabilizer column overhead section.
- Feed is fractionated at main column where overhead is heavy naphtha minus; other cut is kero & bottom is diesel. Wild naphtha is stabilized in stabilizer column where LPG taken at top and bottom if full range naphtha.
- Corrosion problem observed since 2001 --> leaking of overhead condenser of stabilizer and fouling due to corrosion at stabilizer reboiler.
- Operating condition at main column P- atm & T- 125 degC and stabilizer column P - 11-12 kg/cm2.g T- 65-70 deg C.
- Chemical treatment program been used; neutralizer & inhibitor at both column overhead
- Wash water start at stabilizer column since 2007

Current Issue:
- Corrosion still takes place where leak of overhead condensor observed
- Fouling of reboiler occured due to corrosion products

Therefore i would like to get advice on industry experts or anyone whom have experinced such conditions or problem in any of your operating units to share any action/best practises taken.

thank you very much.

regards,
Chandra

[Root]

Hi all,

I'm Chandra working as a process engineer for past 8 years in a refinery. Currently I'm leading a task force to resolve one of the major issue in our plant, corrosion at Condensate Fractionation Unit (CFU).

Background:
- Unit commissioned in year 2000 using sweet condensate as feedstock; same feedstock till today.
- Additional feed stream is wild LPG from Plat former unit to stabilizer column overhead section.
- Feed is fractionated at main column where overhead is heavy naphtha minus; other cut is kero & bottom is diesel. Wild naphtha is stabilized in stabilizer column where LPG taken at top and bottom if full range naphtha.
- Corrosion problem observed since 2001 --> leaking of overhead condenser of stabilizer and fouling due to corrosion at stabilizer reboiler.
- Operating condition at main column P- atm & T- 125 degC and stabilizer column P - 11-12 kg/cm2.g T- 65-70 deg C.
- Chemical treatment program been used; neutralizer & inhibitor at both column overhead
- Wash water start at stabilizer column since 2007

Current Issue:
- Corrosion still takes place where leak of overhead condensor observed
- Fouling of reboiler occured due to corrosion products

Therefore i would like to get advice on industry experts or anyone whom have experinced such conditions or problem in any of your operating units to share any action/best practises taken.

thank you very much.

regards,
Chandra

Hi,
What is sulphur contents in feed (H₂ S and mercaptan sulphur). are giving stipping steam in bottom also?, we have same problem but after stopping stripping steam our problem is minimized.
Toor

[Zauberberg]

Chandra,

You need to provide us with a sketch showing all inlet streams and configuration of the column system, including reboilers and condensers. Only that way we can create a picture of the Unit.

In addition to that, you need to provide the feed stream data, particulary with regards to presence of corrosive components: H2S, Mercaptans, CO2, Water, Chlorides, and any other chemical specie that is known for corrosivity.

What actions did you take so far? Have you analyzed the overhead (condensed) stream, water phase in particular? Please provide more input data.

[smalawi]

Hi

first, identify the following

- name of the feed condensate or crude. condensate crudes cant last for 10 years, so something changed even if the name is still the same

- what type of corrosion do you see. there are many types of corrosion so please check with your materials/plant engineer

- what is the pH of the water in the boot and the wash water. is the ohd water colour black, white or clear ? what is the Chloride level ?

- do you have Chlorides in your LPG ?? does it pass through a guard be before the column ??

- do you have a desalter in this condensate splitter unit ? what do you use as desalter water ??


cheers,

SM