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Furnace Convection Bank Tubes Cleaned Robotically – World First for a German refinery

Heavy fired heater fouling removed using remote technology

Summary

Seeing the commercial and CO2 benefits, this European refinery was willing to invest in Tube Tech to develop a robotic cleaning technology to access deep in between the fins of the convection tubes in order to improve current 10% cleanliness and hopefully achieve an 80%+ production standard clean or better. Furnace Robot was born and delivered a high standard of cleaning in record time.

The client had trialed dry ice which was not successful and water traditional water jetting could not access between the fins and also damaged the refractory.

Challenges

Access for the Furnace robot was via 3 small doors measuring 150mm x 225mm
Time limited to only 48 hours to clean the 15m long furnace on 3 levels
The fired heater / furnace had not been cleaned for 22 years
Hard scale and compact, gummy deposit was sitting between the finned tubes.
No damage to the refractory was allowed
Sulphuric acid vapour needed containing

Disadvantages of Furnace Convection Fins Current Cleaning Options

Hydrant hose wash (off-line): Ineffective. Superficial cleaning. Only used where access doors allow. Only removes the lightest dust. Water damage to refractory.
Chemical/powder injection (on-line): Cleans in one direction with updraft from burner. Only cleans soft to medium fouling. Does not make 360 degree tube/fin surface contact.
Soot blowers (on-line): Only effectively cleans within specific vicinity of soot blower nozzle radius. Does not remove hard scale. Does not make 360 degree tube/fin surface contact as soot blowers are static.
Flame ball (on-line): Can damage refractory, only effective where the sonic blast reaches.
CO²/Dry Ice (on-line): Ineffective – ice melts!
CO²/Dry Ice (off-line): Ineffective. Superficial cleaning of what operator can see or large CO² nozzle can touch. Cannot access between finned tubes. Can only be used where access doors allow. Only removes light dust. Extremely slow.
Traditional Manual Water Jetting (off-line): Ineffective. Superficial cleaning. Can only be used where access doors allow. Water damage to refractory, Cannot access between finned tubes.
Sand/Grit blasting (off-line): Ineffective. Erodes tubes/fins. Lots of dust. Need to collect blast media. Grit sticks between tubes. Creates ‘key’ thus increasing future fouling rates. Cannot access between finned tubes.
Air blasting (off-line): Can only remove light dust. Creates lots of dust. Superficial cleaning. Cannot access between finned tubes. Can only be used where access doors allow.

Solution

The Furnace Robotic removes hard, medium and soft scale off-line. Remote CCTV used to inspect before during and after clean. Access is achieved deep between all rows of tubes and fins. Multiple systems were used simultaneously and were small enough to access the 225mm x 150mm doors. No refractory was damaged. Convection fins received 100% surface contact.

Tube Tech Comment

Mike Watson, Managing Director: “Another world first! This was an extremely challenging contract not least because we were given only 3 weeks’ notice to build 3 robots. Both exciting and rewarding and an unusual challenge for our team of 4 research engineers. This takes fired heater cleaning to a new level and overcomes the ability to clean via small and awkward access doors.

The saving on fuel and CO2 is expected to be substantial. Hopefully this will spell an end to replacing fired heaters / furnaces due to inaccessible fouling. This system is just at home cleaning radiant tubes both horizontal and even vertical serpentine type”.

Mark II Furnace Robot is now in development which will be better and faster than before.

Clients can be contacted via Tube Tech for references.

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Refineries (Onshore - Downstream) Case Studies