A Data-Driven Process Controller for Energy-Efficient Variable-Speed Pump Operation in the Central Cooling Water System of Marine Vessels

In this paper, a data-driven process controller is designed and implemented onboard a typical marine vessel for optimal variable-speed pump operation, leading to the energy efficiency optimization of its central cooling water system. To match variable flow rate requirements due to changes in the vessel's operational profile with respect to plant limitations, real-time process measurements are used as feedback signals to adjust the parameters and set-points of a data-driven process controller with self-tuned proportional-integral-differential control loops, which is realized through a commercial programmable logic controller and regulates the speed of sea water cooling pumps in order to maximize power saving potential during sea-going and cargo unloading periods. Data-driven control establishes system dynamics according to process parameter variation and ensures system reliability through parameter monitoring, regardless of the controlled plant model. The plant power saving potential is initially examined through a practical case study, whereas experimental results provided after the proposed control system retrofit installation onboard a tanker vessel show significant power balance improvement and reduction of diesel generator fuel consumption compared to existing pump throttle control methods, verifying that marine industry can be greatly benefited from this energy efficiency upgrade.