Q & A > Question Details
We encounter polymerisation from phenolic material in the KO drum of the SWS overhead system. As a result, KO drum bottom is frequently plugged and this means that in case of massive carryover from the SWS reflux drum the liquid would not be pumped out of the system. Source of phenols is the FCC. The analyses of the polymeric fouling don't give clarity on the other components, but the appearance is similar to phenol-formaldehyde resins.
Please note SWS reflux drum is operated at 87 C (to avoid ammonium bisulfide deposition) and the downstream system is traced and heated with steam so that the temperature is normally > 100 C (no water is separated in the KO drum in normal operation).
Did anyone encounter similar problems in SWS OVHD systems, and how did you solve them?
 
Answers
29/10/2012 A: Daniele Colle, BP, daniele.colle@bp.com
Yes it is water from FCC unit operating with some Atmospheric Residue (20-30%) in the feed.
Reactor temperature is quite mild (520-530 C) and regenerator is hot at 720-740 C dense phase.
Feed Conradson carbon varies between 1 and 2, O2 excess on the regen is 0.5%.
26/10/2012 A: Marcello Ferrara, ITW SrL, mferrara@itw.it
We already studied this problem for one of our customers. We able to dissolve such deposits and avoid KO drum plugging.
26/10/2012 A: Egbert van Hoorn, Hocon B V, Egbertvh@hotmail.com
It is somewhat unusual to find polymeric deposits in the SWS overhead system, but it has happened before.
Could you confirm that this SWs is treating process water from an FCC unit? The phenols indicate this.
Do you have any pictures of the fouling material?
This is important to understand the problem.
You can send the pictures or the info to egbert.vanhoorn@amineexperts.com.
Is the FCC operating on heavy feedstock or at high severity?