SimTec conducted a Computational Fluid Dynamics (CFD) project for the heavy oil flow inside a submarine pipe, during the fuel feeding of a power generation station on a Greek island from a tanker ship. The pipe consists of a flexible rubber part, which is attached on the tanker and a permanent steel part with a cement coating of 1 [cm]. Both parts have neither insulation nor heating system. The flexible pipe is assumed to have a perpendicular position, whereas the steel pipe of 650 [m] length lies on the sea bottom and has a small inclination towards the island shore. The junction of the two pipes takes place at a sea depth of 10 [m].
The heavy oil enters the pipe at an elevated temperature of 50 [oC], whereas the sea temperature is assumed at [oC] (wintertime). The purpose of the study was to detect possible solidification of the heavy oil (solidification temperature is 30 [oC]).
The simulation was performed by the CFD package FLUENT. Initially at time=0 [s] the pipe was assumed to be filled with sea water. The solution confirmed that the combination of the flow rate (600 [m3/h]) and the feeding temperature prohibit the large-scale solidification of the heavy oil, hence the obstruction of the pipe.
The CFD study included:
- Creation of the geometric model and computational mesh in the pre-processor GAMBIT.
- Solution of the fluid flow inside the pipe along using simultaneously multiphase model (sea water – heavy oil), heat transfer and phase change (solidification – melting).