| 摘要 |
A hybrid riser tower comprises at least one support element 30 and at least one riser element 34 both attached to an upper structure. Those elements extend axially in parallel as a riser column that can be supported buoyantly in an upright orientation, with the riser element hanging from the upper structure. Buoyancy modules 38 are attached at respective load-bearing locations along the length of the support element 30 to impart axial upthrust to the support element when the riser column is upright. The invention also provides at least one supplementary buoyancy module 42 that is attached to the riser element 34 to impart axial upthrust to the riser element 34 when the riser column is upright. This reduces or eliminates weight loading applied by the riser element to the upper structure and so reduces or eliminates compression loading in the support element beneath the upper structure, as experienced particularly in the up-ending phase of installation.
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