MAN Propulsion Package for New Mediterranean RoRo Ferry

By George Backwell at February 23, 2013 03:44
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A RoRo ferry ordered by Italian ferry operator Visemar from the Cantiere Navale Visentini shipyard near Venice, is to be equipped with a complete MAN propulsion package, powered by a pair of 9L32/44CR medium-speed diesel engines.

Visemar RoRo Ferry: Image courtesy of MAN Diesel & Turbo

MAN Diesel & Turbo optimised the propulsion system for the new RoRo, which includes MAN Alpha CP propellors (driven through Renk low friction gearboxes) in close consultation with the shipyard and NAOS, the Italian RoPax ship-design specialist. These project-specific propellors deliver a very high propulsive efficiency, leading to substantial fuel-oil savings for the complete propulsion plant.

Main Engines
The 9L32/44CR engines, which comply with IMO Tier II exhaust gas emission regulations, each develop 5,040 kW at 750 rpm and are complemented by 2 × Renk RSV 900C gearboxes and 2 × Alpha CPP propellers.

These engines use the latest MAN Diesel & Turbo common rail technology which allows flexible setting of injection timing, injection duration and injection pressure for each cylinder: flexibility that allows optimisation of fuel consumption and emissions at any point within its operating profile.

The engine manufacturers have kept the basic concept of its common rail technology as simple as possible with technically proven components integrated into the design. For example, in keeping with this philosophy, MAN does not use a separate servo circuit for activating the injection valve, which not only means less maintenance,  but also a quick and accurate reaction to control.

 Diesel Engine 9L32/44CR: Image credit MAN Diesel & Turbo

Electronic Control & NOx Reduction
The 32/44CR is equipped with the latest generation of MAN’s SaCoSone engine management system which combines all functions of modern engine management into one complete system. Through integration on the engine, this electronic control system forms one unit with the drive assembly, amongst other things providing self-diagnosis functions.

A sufficient reduction in NOx exhaust gas emission to comply with Tier ll, without external additions, is achieved by retarded injection timing, which lowers combustion chamber temperature peaks after fuel ignition. Variable Valve Timing (VVT) an enabling technology of variable Miller valve timing, allows variations in the opening and closing of the inlet valves and can be used to compensate for the increase in Specific Fuel Oil Consumption (SPOC) associated with lower NOx emissions.

A strong Miller effect under high load operation results in an improvement in the NOx-SFOC trade-off. At low load the Miller valve timings are reduced to attain higher combustion temperatures and thus lower noxious emissions.

The NOx – SFOC tradeoff is further alleviated by the use of the manufacturer’s turbochargers fitted with the the latest high efficiency compressor wheels. The resultant higher pressure ration increases the efficiency of the engine and helps compensate for the increase in SFOC normally associated with obtaining lower NOx emissions.

This new ferry was intended to join another vessel on Visemar’s route linking Egypt, Syria and Italy, but due to current unrest in Syria (and in Egypt to some extent) that service has been suspended until law and order has been established, hopefully by the time of the vessel’s delivery in April 2014. 




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