Recently, the world’s first newly‑improved DMD‑Wärtsilä 6RT‑flex68‑D intelligent diesel engine has successfully completed bench tests, with all technical parameters meeting design specifications. Rated at 18 780 kW and with a total weight of 472 tons, the main engine complies with Tier II emission requirements and will be installed on an 180 000‑DWT bulk carrier built by Bohai Shipbuilding Heavy Industry for Greece‑based Transmed Ocean Shipping.
The birth of the 6RT‑flex68‑D diesel engine fully demonstrates that our company keeps pace with global trends in diesel‑engine manufacturing while giving full consideration to customers’ practical requirements. Adopting newly‑released improved designs from Wärtsilä, the engine reduces procurement and manufacturing costs for components and greatly boosts efficiency in main‑engine assembly and commissioning.
Equipped with Delta‑Tuning mode, the 6RT‑flex68‑D diesel engine achieves low fuel‑oil consumption by flexibly selecting control parameters for fuel injection and exhaust valves via the engine’s software control system. This is realized without modifying mechanical components or compromising engine reliability.
Its fuel‑supply unit features a separated design for the fuel‑oil supply system and servo‑oil supply system, enhancing engine stability. The scavenge air box adopts an underslung design, with the moisture separator arranged vertically beneath the air cooler. Compressed air passing through the air cooler undergoes sufficient condensation and separation in the lower section of the scavenge air box. Condensate water drains out of the scavenge air box as completely and rapidly as possible. This significantly improves the quality of fresh air entering the cylinder scavenging space and optimizes engine combustion performance.
Fitted with two new‑type high‑efficiency turbochargers, the main engine delivers higher efficiency with lower fuel consumption, which will generate substantial fuel‑cost savings throughout the vessel’s service life.
The original design of the air‑cooler cleaning system for the 6RT‑flex68‑D main engine used high‑pressure air together with chemical solution for cleaning. This method prevented reuse of cleaning water and involved cumbersome operations. Our technical team revised Wärtsilä’s original design to adopt direct high‑pressure cleaning with chemical solution, achieving excellent results and satisfying the ship‑owner.
In the original layout, the inlet and return pipes for cylinder cooling water were located at the power‑output end of the main engine, whereas the shipyard arranged the water tank at the free end of the vessel. To accommodate the shipyard’s piping layout requirements, our company relocated the cylinder‑cooling‑water inlet and return pipes from the power‑output end to the free end of the main engine, bringing cost savings for the shipyard.
During engine assembly and commissioning, relevant teams worked round‑the‑clock on shift rotation. Issues were reported promptly and resolved at the highest speed to meet the shipyard’s engine‑in‑yard acceptance schedule.
Representatives from the ship‑owner, Wärtsilä, the shipyard and surveyors from ClassNK maintained close attention throughout the project. They kept close communication and coordination with relevant departments and provided strong support for the development work, forming a solid foundation for the successful acceptance and delivery of the main engine.
The successful acceptance and delivery of this new‑type 6RT‑flex68‑D diesel engine marks a further breakthrough for our company in Wärtsilä main‑engine manufacturing and represents another solid step toward becoming a world‑class engine‑builder.