Sulzer RT-flex engines benefits

Benefits of Sulzer Rt-flex engines

1. Smokeless operation
2. Reduced running costs
3. Lower running speeds
4. High reliability and redundancy
5. Common rail
6. Fuel pumps
7. Electronic injection control
8. Ideal for heavy oil
9. Exhaust valve actuation and servo oil systems
10. Ease of installation

Smokeless operation
A clearly visible benefit is smokeless operation at all ship speeds. 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, the 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. 

Sulzer RT-flex engines also comply more easily with the NOX emission limit in Annex VI of the MARPOL 73/78 convention, with the best possible trade-off between fuel consumption and NOX emissions at all loads.

Reduced running costs
Reduced running costs of Sulzer RT-flex engines come from reduced maintenance requirements and a lower part-load fuel consumption. Maintenance costs become more predictable through better-balanced operation and better retention of engine settings over many running hours. Excellent balance in power developed between the different engine cylinders and from cycle to cycle is provided by the common-rail system with its volumetric control. As engine settings are made electronically, the ‘as-new’ settings are retained so that engine performance such as fuel consumption does not deteriorate over time. The better running of the engine will also make for better prediction of maintenance timing and allows times between overhauls to be extended.

Lower running speeds
Precise control of the injection, high injection pressures at low speed, and the sequential shut-off of injectors combine to give steady running at very low running speeds without smoking, down to 10-12% of nominal speed.

High reliability and redundancy
Particular attention has been given to making the RT-flex system reliable. The common-rail system concept also has inherent redundancy, adding to reliability and safety. Redundancy is built-in through multiple fuel and servo oil pumps, together with duplicated high-pressure fuel and servo-oil delivery pipes, and electronic systems. The multiple pumps have adequate redundancy for the engine to deliver full power with at least one fuel pump and one servo oil pump out of action, and only a proportional reduction in power should further pumps be out of action.
World’s biggest common rail
The Sulzer RT-flex concept brings common-rail fuel injection to the modern, large diesel engine. Current jerk-type fuel injection systems combine pressure generation, timing and metering in the injection pump with only limited flexibility to influence the variables. In contrast, the common-rail system separates the functions and gives far more flexibility. It has the distinctive features of precise volumetric fuel injection control, variable injection rate shaping, and free selection of injection pressure.

Well-proven fuel pumps
It employs high-efficiency fuel pumps based on the well-proven design of injection pumps used in Sulzer medium-speed engines. They run on multi-lobe cams to deliver adequate quantities
of fuel to the common rail at the usual high pressure ready for injection. The common rail is, in effect, a manifold running the length of the engine just below the cylinder cover level. It provides a certain storage volume for the fuel oil, and has provision for damping dynamic pressure waves.

Electronic injection control
Fuel is delivered from the common rail through injection control units to standard fuel injection valves. The control unit for each engine cylinder regulates the timing of fuel injection, provides
control of the volume of fuel injected, and sets the shape of the injection pattern. The three fuel injection valves in the respective cylinder cover are independently controlled so that they may be programmed to operate separately or in unison as necessary. 

Ideal for heavy fuel oil
Sulzer RT-flex system is purpose-built for operation on standard grades of heavy fuel oil. For this reason, it incorporates certain design features not seen in other common-rail engines using middle-distillate diesel oils.

Exhaust valve actuation and servo oil systems
The Sulzer RT-flex system also includes exhaust valve actuation and starting air control. The exhaust valves are operated in much the same way as in existing Sulzer RTA engines with a hydraulic pushrod but with the actuating energy now coming from a servo oil rail at 200 bar pressure. The servo oil is supplied by high-pressure hydraulic pumps driven from the same gear drive as the fuel pumps. The electronically-controlled actuating unit for each cylinder gives full flexibility for valve opening and closing patterns. This unit utilises exactly the same rail valves as are used for controlling fuel injection.

Ease of installation
Although RT-flex engines can be called revolutionary, they are fully compatible with the RTA engines in relation to engine room installation and shipboard operation. This means that the main outline dimensions, foundations, key engine parameters, integration in ship automation and other interfaces of the RT-flex engines are identical with those of the corresponding RTA engines.
It should also be noted that at heart the RT-flex engines have the same structure, running gear and processes as the existing RTA-series engines. In addition, vital parts such as the fuel injectors and exhaust valves of the RT-flex are fully compatible with those of RTA engines.