Cleaning with Supercritical CO2
Innovative method to clean umbilicals and control lines.
The Supercritical CO2 flushing system (SCCO2) fits perfect for control lines and umbilical’s, because of the low-pressure drop over long distances, which can exceed 20 km, with a small inner diameter lower than ¼”. This means that turbulent flow can be maintained all the way thru, and a cleanness of AS4059 Class 3 / ISO 4407 12/9 has made proof of concept in testing. However, it can also be fitted to other appliances.
Conventional flushing is a well-known method to clean to the inside of systems, and a turbulent flushing flow is mandatory for cleaning effectively. A challenge, when using conventional flushing fluid in systems like umbilicals and control lines, is the ability to keep a turbulent flow all the way through.
It basically requires a pressure drop of more than 30,000 PSI. This kind of pressure drop exceeds the maximum test operational pressure, which most pipe systems are designed to withstand.
The Solution is Supercritical CO2
The reason of this cleanness and low-pressure drop is that Supercritical CO2 has the same carrying capacity as oil, but the viscosity is 10 times lower than water. This makes it a lot better than the conventional flushing systems that has a pressure drop of over 60.000 PSI over ¼” OD 13.000-meter Control-Line, were SCCO2 has a drop of below 3.000 PSI and maintains a Reynolds No. of approximately 20.000. To maintain a turbulent flow, you need a Reynolds number higher than 3000, and in long distances, this is not possible with conventional flushing. The state “supercritical” is a state that is not gas, and not fluid, but a state in between these two. This means that is has the same benefits as both of those two states.
Advantages
• Higher cleanliness & greater operational reliability of the system
• Method, friendly to the environment
• Simple, flexible and easy-to-operate equipment
“An Innovative Revolution”
The unit is built using the latest technical advances in industrial PC control, which includes a 24” color touch display, optimized for easy and intelligent control.
Via an internet connection, it is possible to create remote technical support.
After end cleaning – It is possible to draw complete log files of the work flow.
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SCCO2 Flushing Technology
Research indicate that 80% of all failures in fluid transfer systems are caused by contamination.
Contamination, which also causes huge gaps in both safety and reliability while shortening the lifespan of, for instance, subsea systems, often consisting of and controlled by 10-20-30 km long umbilical’s/control-lines, with no efficient cleaning option.
Consequenses of Subsea System Contamination
A fatal outcome of lacks in reliability and safety of a Subsea system is seen by the Mexican Gulf Disaster, April 20, 2010. Through this disaster, eight different safety systems failed – two of them (Slow operating valves), most likely, due to system contamination. Today, huge amounts of hydraulic fluids still vent in to the North Sea, because of contamination blocked control-lines and exceeding pressure. Flushing the lines using conventional methods is not efficient and provide too high pressure loss. There has not yet been found the proper way to clean the systems, the system life span decrease and the affair is costly.
After this disaster, and after several inquiries from our customers about flushing challenges and cleaning systems of several kilometers, and small inner diameter pipes. Ocean Team Group (OTG) started a R&D project to solve these issues, and spend five years in developing the patented solution. This solution is the supercritical and liquid CO2 flushing unit (SCCO2 Unit), that have proven to be a great success!
This unit is also equipped with SAT internet for external connection, and have extensive data logging.
Proof of Concept
November 2014, OTG executed a Proof of Concept test on a 6.500m long dual ¼” OD control-line with a great outcome and with several 3rd party supervisors with a Major North Sea operator, present. The test was re-performed in January, 2015, using an equal coil. It came with the same impressive outcome that was better than anyone could have hoped for. The result exceeded the standard subsea requirements.
The offshore cleanness requirements are AS4059 grade 6 (NAS1638 Grade 6), and with the SCCO2 unit, an impressive cleanness of AS4059 Grade 3 (NAS1638 grade 3) was obtained.
Furthermore, in November 2015, it was proven again, by flushing a 13 km ¼” OD control-line with even more impressive results with these length (which can exceed 20-30 km). This will increase the safety of the systems, save a lot of money, and at the same time save the environment from oil spill disasters.
For Multiple Applications
The SCCO2 flushing technology is usable for other applications, with tendencies to pipe blocking. This is possible because of the very high solvent effect, that can dissolve even wax, and other a-polar substance.
Conclusively, the CO2 flushing technology is for constructional release and after installment for service cleaning to extend the life of the system. This system is therefore perfect for Control-Lines subsea systems, and Umbilical’s. The marked demand in the subsea industry have shown this: There are longer and longer pipes, in deeper and deeper waters, were the solenoid valves in the Subsea Control Module (SCM), and safety valve have smaller tolerances. Efficient and safe subsea operation, demands a high cleanness level and this have previously not been possible, until now. Before it have not been possible to obtain turbulent flow, and because of the high pressure loss in the narrow pipes, it has only been possible to filtrate the oil.
Consequently, unforeseen shutdowns, blocked pipes and short system life are a costly entry on the financial accounts.
Ocean Team Groups patented solution, saves money, extend the life of the system, keeps the systems operational and safer to the environment.
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