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Please give us any suggestions for the online cleaning of Vacuum column overhead condensers. The Condensers are suspected to be fouled. What can be the fouling material in the condensers?
 
Answers
10/08/2012 A: Saswat Panda, Reliance Industries Ltd, saswat.panda@ril.com
At times if entrainment starts from top of vacuum column and there are chances that the end point of hydrocarbon lending in ejector hot well will increase from normal 250 - 270 deg C to as high as 550 deg C. If this happens then it is for sure that the high end HC like LVGO/ HVGO will get scaled up on the tube surface due to subcooling and will reduce the condensation duty.
As a first step preheating of the CW coils after draining CW by LP/ MP steam can be tried. This helps in raising the skin temp of coils resulting into removal of formed scales. This will not affect the mechanical integrity of coils but certainly helps in improving the condensation duty.
Note similar process side fouling of ejector condensors
03/08/2012 A: J ROUT, IPESS, jrout86@gmail.com
Overhead condensers should have reverseflow/back wash facility in cooling water side. Periodic reverse flow in tubes would reduce the occurance of fouling. This is done online.
27/07/2012 A: Mike Watson, Tube Tech International Ltd, mike.watson@tubetech.com
Tubetech international currently have a research project which is to develop a live online cleaning system both the tune signed and the thin side of ankle condenses. The likely fouling will be a mixture of hydrocarbons and iron oxide. Be aware of under scale corrosion affecting the integrity of the tubes especially near the header box end. Tubetech are able to clean the header boxes back to bare metal without taking both ends off.
27/07/2012 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Most likely fouling is on the cooling water side. The exchangers are typically located high in the air and it is difficult to get the desing cooling water flow to the exchangers. The reduced flow promotes fouling. The combination of reduced flow and subsequent fouling has double effect on exchanger performance.
If the vacuum tower overheads have enough acids, you could potentially start corroding the condensers and foul the outside of the tubes with corrosion deposits. Acid sources are chlorides, organic acids from naphthenic acid degradation, and CO2 from both naphthenic acid degradation and air leakage. If you are not monitoring the pH of the water from the vacuum seal drum you should start doing so. If the pH is low, your chemical supplier can analyze the water to see what the source of acids is.
27/07/2012 A: Marcello Ferrara, ITW SrL, mferrara@itw.it
There are a number a potential foulants in the overhead of the Vacuum tower.
We can address all of them with our patented Online Cleaning technology.