froeken
Petroleum
- May 15, 2009
- 2
I am working on a project on the water disposal from a FPSO-ship. Water for disposal is lead to a caisson: A 30 m 24'' vertical pipe leading water down under the boat. The inlet is tangential and sloped downwards so that water will flow down in a vortex leaving the middle of the pipe gas filled. Excess gas displaced by water flow and wave motion is vented to the atmosphere through a swan neck vent, so that the pressure in the caisson will be approximately atmospheric at all times.
Caissons are sized using the Froude number:
Froude number = V/(D× g)^0,5
where
V is the velocity assuming full pipe in m/s
D is the pipe inner diameter in m
g is the gravity constant in m/s2
Litterature sizing limitations range from maximum Fr from 0,3 to 0,7. With expected flow rates we will end up with Fr=0,7 if we do not build a bigger caisson.
Do anyone have experience with sizing caissons? What is the optimal slope of the inlet pipe? Will the caisson pressure be steady with a froude number of 0,7? 0,5? 0,3?
Caissons are sized using the Froude number:
Froude number = V/(D× g)^0,5
where
V is the velocity assuming full pipe in m/s
D is the pipe inner diameter in m
g is the gravity constant in m/s2
Litterature sizing limitations range from maximum Fr from 0,3 to 0,7. With expected flow rates we will end up with Fr=0,7 if we do not build a bigger caisson.
Do anyone have experience with sizing caissons? What is the optimal slope of the inlet pipe? Will the caisson pressure be steady with a froude number of 0,7? 0,5? 0,3?
