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We are facing frequent choking problem in phenolic water stripper bottom pump strainer. Phenolic stripper is operated at 1.4 kg/cm2 of top pressure. Column top temp is 93 deg C & bottom temp 129 deg C. Column bottom section has reboiler which use saturated LP steam (157 deg C). It is prudent to note that phenolic water feed pump is not getting choked. Can anyone have a solution to overcome the choking issue??
 
Answers
21/12/2015 A: Egbert van Hoorn, Hocon B V, Egbertvh@hotmail.com
A good investigation of your stripper should be carried out. It would seem that your top temperature is too low, so you should apply more heat/steam.
This is however not everything that can be wrong.
If you require more details, please mail me.
20/12/2015 A: Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
What is the source of the Phenolic sour water ? Is it Coker + FCC ? Coke fines escape into sour water from the columns due inadequate mid-wash flows. These will be kept in oil phase with the aid of suitable chemicals, but at times slip into sour water stream also. Feed pump strainer may not be choking because the material sour water (lower pH) and the coke fines may be loosely flowing. Higher HC ingress into sour water strippers result in coking on the Sour water stripper trays and that can choke the stripper bottom pump strainers. Also Stripped water pH gets boosted in the Sour water strippers and the coke fines must be getting binded into larger particles. If these particles are not removed in the Sour water stripper, they land up in desalters and finally surface in the CDU overhead Naphtha / TPA circuit. Check the Chloride levels in stripped water and take corrective action to prevent entry of Chlorides into sour water strippers. Check if the sea water coolers in the system are contributing to these chlorides. Fine tune the Caustic injection dosage into the stripper (if it is provided).