Heat Exchangers (Crude Trane) U-Tubes Polished in Five Hours
Energy efficiencies increases three fold
Summary
As a company which has built its considerable reputation on innovation, Tube Tech International is constantly reviewing cleaning methods. When new processes and practices are refined at Tube Tech they are recommended to client companies for future implementation. This was the case with the cleaning of two crude oil heat exchangers at an oil refinery in Essex.
Challenge
- One of the most crucial cleaning operations at a refinery is the crude oil heat exchanger trane involving considerable and potentially-expensive downtime when taken off line.
- Reducing downtime can save hundreds of thousands of pounds.
- The most common forms of cleaning methods employed by competitors have been chemicals or traditional high-pressure water jetting each taking an average of three to seven days respectively.
- Neither process consistently achieves the optimum removal of tenacious carbon and coke deposits that form within the “U” bends nor the straight tubes.
- Chemicals cannot negotiate the blockages often found in crude exchangers plus the environmental, waste issue is always present.
- High-pressure jetting can be slow, or lances can become bent if confronted with blockages. Moreover, flexible and rigid high-pressure water lances never negotiate the hairpin bends.
Solution
- Tube Tech has developed the ability to spade off, debolt, clean and rebolt each exchanger speedily enough so that other exchangers within the same trane could support the production load for this short period.
- This involved a new three-stage process which starts with a Rotaflex Softdrill being fed down the tubes using a patented lance feeding mechanism.
- This was followed by a rigid lancing system utilising intelligent metals that reform to its original state after negotiating the bends.
- Finally the rotary turbine darTT is utilised to rotate down the tubes, scouring and polishing the internal bore including the bends.
- A special mock-up was built for the client at Tube Tech’s headquarters to prove the three-stage process would be effective.
- Rigid lances were modified to go around narrow hairpin tubes at 1000 and 2000 bar water pressure.
- The rotating turbines were adapted to negotiate bends without jamming.
- The hairpins were cleaned back to bare metal, indicated by the gingering up of the carbon steel tube surface.
- Downtime was reduced to an incredible five hours.
- The effect of such an efficient clean was more than $1million in fuel savings through a reduction of furnace inlet temperature of 12C.
- After cleaning just one hairpin exchanger and polishing the bends Tube Tech methods increased their energy efficiencies almost 3 fold up from 150,000 when using traditional chemical and pressure jetting systems to a massive 400,000 kJ /C-HR.
Tube Tech Comment
Mike Watson, Technical and Managing Director: “Our philosophy to challenge tradition far exceeded our clients and to be frank even our own expectations. The ‘horses for courses’ approach is key to establishing better results backed by our on-site experience. This achieved yet another landmark in cost saving exercises targeted at refinery downtime and production performance. While we have an excellent success rate at improving clients’ cleaning practices, we are occasionally surprised at the level of improvements of knock-on effects achieved especially when using newly-developed techniques.
Clients can be contacted via Tube Tech for references.
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