Far Eastern V.C.F.E. cleaned and inspected
A Vertical Combined Feed / Effluent Exchanger (Texas Tower) at a large refinery in Asia suffered from massive performance drop caused by tube bore blockages compounded by inaccessibility to clean using traditional cleaning technology and several attempts at using chemicals. Chemical as we all know does not go through blocked tubes, takes the least path of resistance and can sit in the top of a blocked tube for a long time adding to the tube wall loss. Chemical cleaning the external tube surface (Shell side) of a texas tower is even more risky
as chemicals cannot achieve the desired shear force to react and flush deposits away from the numerous baffle plates causing deposits to remain and swell having absorbed moisture, swollen and causing more of a problem between the tubes.
Previous cleaning attempts had been unsuccessful due to the limitations of traditional “jetting” technology unable to unblock the 25m long tubes as they create dangerous hydraulic back pressure with their slow retro firing jetting nozzles i.e. 20 minutes to several hours per tube thereby taking up to 50 shifts at best going back online with many blockages left behind continuing the under scale corrosive action.
Being on the critical path, there was a limited time frame in which to complete the cleaning. With typical V.C.F.E. downtime costs ranging from $100k to $500k per day, overrunning the shutdown deadline was a great concern.
Shell Global Solutions challenged Tube Tech to develop a technology to remove hitherto unknown deposits via limited access, as well as requesting tube wall integrity results.