Genset Upgrade for Engine 'Workhorse' by MAN Diesel & Turbo

By George Backwell at March 18, 2012 00:52
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MAN Diesel and Turbo said last week it will up-rate its popular four-stroke diesel GenSet L23/30H by almost 10% of current values (any more than that and the design would have to be submitted to classification societies for ‘Type Approval’ thus increasing costs and taking more time).

Introducing the upgrade, MAN adds a footnote lauding this particular engine, the classic 23/30 model first introduced by subsidiary Holeby fifty or so years ago, as one of its ‘original workhorses’, mentioning too an increase in orders for the new version of this, the Mk.2 engine .

On the understanding that a workhorse is something that does a large amount of dull or routine work faithfully —  providing a ship’s electrical power seems to fit  —   then the title is well-earned by the GenSet. What made it so popular?

Genset Turbocharger Detail: Photo courtesy of MAN

Electricity Generator Workhorse in the Making

Unsurprisingly it was the saving in fuel costs offered by the alternator’s driving force medium speed diesel engine that first attracted customers, made possible by the unifuel principle, which meant in large ships that these auxiliary engines (normally a minimum of three) ran on the same heavy fuel oil as the two-stroke main engine. In port a three-way valve enabled the engine to run off marine grade diesel oil from a separate fuel tank.

The unifuel system also came to integrate the cooling water, and starting air systems between main and auxiliary engines to make best use of engine room space with simplified operation of plant and its maintenance. When in due course it became apparent that expenses for this GenSet’s maintenance and repair were among the lowest in the industry, market success for the new auxiliary was assured.

The common fuel system, shown in the block diagram below, features extensive fuel cleaning by centrifuges to remove solid and liquid contaminants from the common fuel oil, of major importance to the trouble-free fast revving diesel engine driver.

Uniflow Fuel Supply: Schematic courtesy of MAN Diesel & Turbo

GenSet Upgrade – The Main Features

Design improvements, the latest in a long line over the years, now give the MAN L23/30H Mk.2  engine an increased rating of 15 kW per cylinder at the same revolutions as the existing model (i.e. at maximum 900 rpm)

The Mk. 2 will be matched to comply with IMO MARPOL Tier-ll requirements.

A different turbocharger is fitted to the new version –  MAN type NR/R is replaced with the TCR type which the manufacturers say offers easier maintenance with a reduced number of parts; an extended interval between inspections, and easy access to the compressor wheel.

In common with the its predecessor the improved engine is expected to share the GenSet’s extremely long TBO of 16,000 hours when run at 720/750 rpm or 12,000 hours at the maximum 900 rpm.

Click here for more detail of the uprating (downloadable as a .PDF file).


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