The icebreaker machineries should meet the following requirements: 1. maximum output at a wide range of propeller revolutions; 2. capacity for abrupt variations of load and reversals of direction; 3. operational flexibility; 4. ability to operate at a wide range of air and water temperatures; 5. resistance to ice loads; 6. special qualities which make it fit for a long standing season; 7. reliability. Let it be settled that the steam-operated icebreakers complied well with the requirements listed above. When abandoned, the steam engines of the icebreakers could not be replaced by diesel engines direct-connected to the propelling system, as were those of the merchant ships. Instead, a diesel-electric system was developed to replace the steam engine. The first diesel-electric icebreaker, with a diesel engine output of 3300 SkW, was delivered to the Finnish State in 1939. The diesel-electric system is based on Ward Leonard regulation. In all icebreakers presently in operation that system forms the base, even though especially the electronics have developed considerably.The choice of diesel is greatly dependent on the need to minimize the weight of the machinery. In the seven icebreakers that were built between 1958 and 1970 the main machinery consists of four two-stroke diesel generators with mechanic scavenging. The diesels are of trunkpiston type. In the icebreakers built in the late 1960's (diesel output 10000 kW) it took some 8 seconds to reverse the direction at full speed. The development in the electrical regulation technics made it possible to use turbocharged four-stroke diesels in the icebreakers built in the 1970's without having any significant slow-down of the direction reversal operation. In new icebreakers, the turbochargers are prevented from pumping by electronic load relief regulation circuits for the generator loads. The machinery output that an icebreaker needs varies greatly. In the newest icebreakers (18400 kW} special attention has been paid to the flexible use of the reserve power. The main machinery consists of five diesel engines with their own pump and heat exchange systems. The main engine can be started as easily as a car engine and the engine can be connected to the network within a minute if necessary. The flexibility of power use has been optimized in the so called power-plant type icebreakers, where connection to the network does not cause elimination of the power of the propeller circuit for the time of the connection.


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    Titel :

    Special characteristics of icebreaker diesel machineries


    Weitere Titelangaben:

    Besondere Charakteristika von Dieselmotoren für Eisbrecher


    Beteiligte:
    Harjula, A. (Autor:in)


    Erscheinungsdatum :

    1981


    Format / Umfang :

    17 Seiten, 7 Bilder


    Anmerkungen:

    (+ 1 S. Discussion)


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Datenträger


    Sprache :

    Englisch




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