Sulzer RT-flex. Low exhaust emissions
A clearly visible benefit of Sulzer RT-flex engines is their smokeless operation at all ship speeds. It helps give a “green” image.
This was well demonstrated in the testing of the first RT-flex engine and during the sea trials of the Gypsum Centennial.
The superior combustion performance with the common-rail system is achieved by maintaining the fuel injection pressure at the optimum level right across the engine speed range. In addition, selective shut-off of single injectors and an optimized exhaust valve timing help to keep smoke emissions below the visible limit at very low speeds.
The precision and flexibility in engine setting given by the RT-flex system facilitates compliance with the NOx regulation of Annex VI of the MARPOL 73/78 convention, usually referred to IMO NOx regulation.
The flexibility of the RT-flex engines will also allow a lowering of NOx emissions if the corresponding increase in BSFC is acceptable. With common-rail injection, a wide variety quantity of fuel can be divided, for pre-injection, triple injection, etc. The Sulzer RT-flex engine, with its individual fuel valve control, also has the unique ability to vary individually the injection timing and sequence between the three fuel injectors in each cylinder and thus to generate a tailor-made heat release.
In engine tests, this degree of flexibility has proved useful to reach NOx emissions of 20 percent below the IMO NOx limit with a moderate BSFC increase of 2.3 percent.