Q & A > Question Details
Please tell me the normal PH limit supposed to have at the NHT Stripper Column Overhead drum water boot sample. Currently, we are getting ±1 which is very low. Please enlighten me whether it could be the effect of wet H2S alone or it could be the cause of combined effect of wet HCl and H2S which might carry over during the wash water injection from reactor effluent Separator drum to the Stripping Column Overhead Drum.
FYI- 10 wt ppm CHIMEC 1044 is being injected at the inlet of stripper overhead air cooler continuously.
 
Answers
19/09/2018 A: Andrea Fina, CHIMEC, afina@chimec.it
pH = 1 for a NHT Stripper Column Overhead drum water boot sample (if I understand correctly) is an extremely low value and exposes the unit to severe corrosion. Despite the high efficiency of CHIMEC 1044, any film forming corrosion inhibitor cannot perform properly at this pH. A pH of 1 is a symptom of strong acid presence, most probably HCl formed in the reactor by the cracking of organic chloride. You should notice the same also in the water drained from the NHT separators upstream the stripper column. I’m asking you kindly to contact your CHIMEC representative or to write me an email to solve this issue.
15/03/2017 A: Eric Hennings, Technip Stone & Webster, EHennings@technip.com
If the low pH is correct, I would suspect organic chlorides in the naphtha feed. Analyze water for chlorides. Try to eliminate sources. Sources can be machine shop solvents in slop, paraffin dispersants in crude or other chemicals. Often, organic chlorides will also show up as low pH in CDU overhead..
14/03/2017 A: Amol Palve, Dorf Ketal B V, amolp@dorfketal.com
The normal pH range is 5-7 in most of the cases. There is possibility of under deposit salts and wash water rate/source is equally important. Dorf Ketal representative shall help to discuss and propose effective solution on this.