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In our Crude Unit we have LGO pump around heated Light kersosene stripper. The reboiler is no longer giving heat duty and hence Kero flash became limiting. We put stripping steam also in kero stripper, but no gain in kero flash.
Is anybody using antifoulant for correction?
 
Answers
23/01/2011 A: A S Vishnu Ram, RIL, vishnu.selvaraj@ril.com
As the specification given by you is limited, I can suggest you few points in general,
1. You might have over heated the reboiler one or in commissioning which might have created charring (Polymer formation) in the outside of the tube surface which results in poor heat transfer. This can be confirmed by checking the trends of LGO outlet temp from the commissioning.
2. The pressure drop across the Kero Pump around draw might have increased due to the ammonium chloride salt deposition over the trays. Also the Kero trays are prone to corrosion when sulphur/TAN is higher.
3. I also suggest not to increase the Temp of LGO inlet to reboiler over design, which may lead to thermal shock.
4. During commissioning of such a kind of reboilers the minimum incremental of hot fluid will cause leakage also increase the fouling in no time. So a considerable amount of hot fluid flow, which shows minimum temperature diff. across the exchanger to be given initially and then it can be increased to max.
5. Check the reboiler design for the critical heat flux data and relate with the presence. I think you must be over doing the reboiling....
18/05/2010 A: keith bowers, B and B Consulting, kebowers47@gmail.com
Are you implying that the kero reboiler is fouling? Which side? Why? This is not a usual problem area.
Perhaps you are allowing the kero side to evaporate to dryness? Should always be at least 25% liquid remaining in kero-return to the column
How is heat input to column regulated? Is LGO circulation throttled or is kero side restricted? Is kero side thermo-siphon or pumped?
Too many factors unspecified for me to provide any possible assistance