Furnace cleaning of a heavily fouled convection section using remote technology
The client had trialled dry ice and traditional water jetting but both were unsuccessful and had even caused damage to the refractory. However, seeing the commercial and CO2 benefits, this European refinery was willing to invest in Tube Tech to develop a robotic, furnace convection section cleaning technology. The intent of the robot was to access deep in between the fins of the convection tubes to improve the current 10% cleanliness to, at least, an 80% production standard clean. Thus the Furnace Robot was born and truly did deliver furnace cleaning of a high standard in record time.
- The fired heater / furnace convection section had not been cleaned for 22 years.
- Access for the Furnace robot was via 3 small doors measuring 150mm x 225mm.
- Time limit of only 48 hours to clean the 15m long furnace on 3 levels
- Hard scale and compact, gummy deposit was accumulated between the finned tubes.
- Furnace cleaning procedure was not allowed to damage the refractory
- The furnace convection section cleaning robot managed to remove hard, medium and soft scale deposits while the refinery was off-line.
- Remote CCTV allowed Tube Tech to inspect work before, during and after furnace cleaning.
- The furnace robot managed to access deep between all rows of tubes and fins.
- Simultaneous, multiple systems that were small enough to access the 225mm x 150mm doors achieved 100% surface contact of the convection fins.
- No refractory was damaged.
Other Furnace Cleaning Options & their Disadvantages
Air blasting (off-line): Can only remove light dust. Creates lots of dust. Cannot access between finned tubes. Can only be used where access doors allow.
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.
CO²/Dry Ice (off-line): 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.
CO²/Dry Ice (on-line): Ice melts!
Flame ball (on-line): Can damage refractory, only effective where the sonic blast reaches.
Hydrant hose wash (off-line): Only used where access doors allow. Only removes the lightest dust. Water damage to refractory.
Sand/Grit blasting (off-line): 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.
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.
Traditional Manual Water Jetting (off-line): Can only be used where access doors allow. Water damage to refractory. Cannot access between finned tubes.
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.
“Due to the good experience we had with Tube Tech’s innovative cleaning of our V.F.C.E. (Vertical Combined Feed Effluent Exchanger – Texas Tower) that you did for us, we were confident that you would be able to provide and deliver an innovative technology.
We knew that your technology would cost significantly more than standard cleaning methods, but were confident with your track record that the return on investment would be worthwhile, we also knew that standard cleaning companies would most probably not be able to deliver the required results.
We thought to either replace the upper fired heater section or clean it. Replacement would have been 4-5 times more costly than cleaning and due to the good experience with Tube Tech, we decided to give you a chance.
As you know, overall cleaning result was very satisfactory and allowed us to recover cleaning costs faster than we expected.”