Abstract
This paper describes Kvaerner’s prototype subsea multiphase pump system and the DEMO 2000 development program (current test completion date 2nd Q2001). Reference is also made to service proven sub-systems, components and subsea expertise incorporated into the pump module and system design. Availability and reliability consideration together with novel plans for the future is presented.
The Subsea Multiphase Pump and motor are packaged into a modular system solution that is readily adaptable to template and manifold configurations and maximises the use of existing qualified components and sub-systems. A guidewireless system is adopted and Kvaerner’s design ensures self-alignment upon installation at simple flowbase interfaces, making it ideal for deepwater applications. Due to the individual 40 tonne weight, and moonpool dimensions, of both flow base and pump module, light monohull vessels can be utilised to execute installation and retrieval.
The pump unit is Bornemann twin-screw design, service proven and modified for subsea use up to 2000-meter water depth, driven by an oil-filled Loher electric motor that provides efficient power with corresponding low weight. Some main pump features are flexible operation covering all gas-liquid ratios together with tolerance for slug flow and some sand. Of particular importance, compared to centrifugal pump designs, the twin-screw volumetric arrangement is able to maintain the pressure boost specification independent of gas content at the pump inlet, and without an upstream mixing tank.
Proposal of a stage-by-stage design method and its application on a multi-stage multiphase pump based on numerical simulations
