By integrating MHI-MME’s waste heat recovery system and energy saving power generation system (WHRS) with Wärtsilä’s operational control technology for shaft generator systems, the new solution results in more energy efficient ship navigation and an improved Energy Efficiency Design Index (EEDI).
A notable innovation is the combining of a power take off/take in (PTO/PTI) shaft generator system with the WHRS to improve the stability of the WHRS. Depending on the load of the main engine and the ship’s network, the WHRS sometimes produces electrical energy in excess of that needed by the network. Such energy can be utilised via the PTO/PTI generator and at full load, the surplus energy can be used to assist the ship’s drive by being applied directly to the propeller shaft. At low main engine load, the WHRS can be operated in parallel with a diesel generator set. Parallel operation with a shaft generator via PTO operation is also easily implemented.
The patented design connects the WHRS generator into the DC link circuit of the PTO/PTI shaft generator rather than directly into the mains. This allows operation of the WHRSat reduced speed to create higher efficiency of the turbine system at part load. In so doing, it avoids the necessity of speed regulation valves, which cause throttle or bypass losses.
”When two technology leaders combine their fields of expertise, as is the case here, a solution can be created that raises efficiency to a new level. This will produce obvious benefits for ship owners and operators, and we are proud to be cooperating with Mitsubishi in this exciting development,” says Peter Rogers, Director, Power Conversion, Wärtsilä Marine Solutions.
”We are moving forward various energy-saving technologies and can expand our portfolio with this new solution, which we are quite convinced will satisfy present market demands for increasing environmental awareness. We wish to thank Wärtsilä for its high-quality collaboration that has made it possible,” says Tomoo Kuzu, Executive Vice President of MHI-MME.