The solution combines MHI-MME’s waste heat recovery and energy-saving power generation system (WHRS) with Wärtsilä’s operational control technology for shaft generator systems in order to offer more energy-efficient ship navigation and better Energy Efficiency Design Index (EEDI) for marine vessels.
A Wärtsilä power take-off / take-in (PTO / PTI) shaft generator system has also been integrated into the WHRS to improve the stability of the solution.
MHI-MME noted that the WHRS sometimes produces surplus electrical energy depending on the main engine load and the ship’s network, which can be used to drive the propeller shaft via the PTO / PTI generator.
The surplus energy can be directly applied to the propeller shaft at full load to help the vessel to move forward.
Furthermore, the WHRS system can be operated in parallel with a diesel generator set when operating with a low main engine load.
MHI-MME and Wärtsilä have already patented the new solution’s design, which connects the WHRS generator into the DC link circuit of the PTO / PTI shaft generator rather than directly into the mains power.
This function enables the WHRS to operate at a reduced speed to facilitate the greater operational efficiency of the turbine system at part load, as well as help to avoid the necessity of speed regulation valves that could cause throttle or bypass losses.
The companies further noted that a variety of MHI-MME energy-saving technologies were used to develop the new solution.