A riser system for transporting a slurry from a position adjacent to the seabed to a position adjacent to the sea surface

摘要

The system comprises a first and second risers 1 / 2. Slurry pump system 17 transports slurry up one of the risers. Waste water pump system 107 returns waste water down one of the risers. The slurry pump system and waste water pump system are selectively connectable to each of the risers to allow each riser to be either a slurry riser 1 or a waste water riser 2. There may also be a third and forth riser. There may be a plurality of slurry pumps spaced along the length of a riser. The riser system can be made from a plurality of riser modules. There may be two types of riser module, a duct module comprising at least four ducts with no lateral ports and a pump module comprising at least four ducts of which at least one is provided with lateral inlet and outlet ports. Further independent claims specify alternative combinations of the apparatus.