Upgrade for engine and production process MEDIUM-SPEED ENGINES
L
AST year, the MaK M20 engine range was upgraded to the M20C version. It
is the latest development since the M20 was initially introduced in 1992. At that time it was part of the first of MaK’s medium-speed long-stroke marine diesel generation, which has now expanded to include the M25, M32, and M43 models. Since its introduction, around 1200 M20
engines have been sold, with an estimated 60% for genset usage and 40% for main propulsion. About half of the engines are operated with heavy fuel oil, and 900 engines are thought to be currently in service. They have been installed aboard various different types of vessel, for example on Uran, a harbour tug operated by Tripmare in Italy, the tanker Dordogne of Petromarine, France, and an M20 also supplies the electricity on the five-star cruise ship Deutschland. Another design revision occurred in 1997,
when power was increased by 10% at the same time as an emissions reduction was built in, to comply with International Maritime Organization (IMO) regulations. This current update is claimed to make the
M20C safer and more reliable than previous versions. A reduction in the number of engine parts required is said to have a positive effect on reliability, but a multi-component two- circuit cooling water system is still employed, as it is seen to be a sustainable investment. A high-temperature circuit avoids potential
low-temperature corrosion inside the engine and enables better use of rejected heat, for instance as fuel tank heating or fresh water generation. Against this, the low-temperature circuit improves lube oil and charge air cooling, facilitating cooler combustion and
drop limits set by classification societies. A single pipe exhaust system reduces the
pipework required, with the remaining pipe being mounted close to the engine block, giving fewer harmful vibrations. The charge air cooler is said to improve engine reliability by having a smaller amount of sealing surfaces. Maintenance is also facilitated by the
MaK 8 M20C propulsion engine.
connectors at the end of every exhaust pipe segment, enabling quick assembly and disassembly. The M20C’s exhaust system cladding is compact and complies with the latest SOLAS regulations, which aim to protect the safety of the engine crew. The crankcase has also been altered and
fewer emissions. The combination of the two circuits is thought to increase the system’s efficiency. Another addition which is claimed to
develop efficiency and reliability of the M20 is the use of the high-performance turbocharger, KBB HPR4000/5000. Its design delivers more charge air without the need for water cooling, which reduces thermal load on the engine, and the charge air cooler itself has been redesigned. Pulse charging is available as an option,
however, the modified single-pipe exhaust system gives the same performance at seemingly increased reliability, easier maintenance, and reduced installation space levels. Testbed trials with an MaK 8 M20C have suggested that the single-pipe exhaust system has little effect on engine acceleration time. In a genset application, the frequency drop in both a 3-load and a 4-load step system is less than 5%, which is below the speed-
among the new features are improved crankcase covers, a modified lower valve drive, and a new speed governor drive. The governor drive is of the same design as the M32C and M43C engines, being a complete module with fewer parts and a lower wear rate. The governor drive by gearwheel with straight teeth requires no further adjustment, and the crankcase sealing has been strengthened in order to prevent fuel oil from contaminating lube oil. Elements of parent company Caterpillar’s
ACERT technology have been designed especially for MaK medium-speed engines, including Flexible Camshaft Technology (FCT) and Caterpillar Common Rail (CCR). FCT is available for M32C and M43C engines; additionally, CCR is being introduced for the M32C. The crankcase of the M20C is built to incorporate this technology, and each one delivered is able to be retrofitted for future customer demands. To utilise the advanced M20C features with
existing engineroom designs, the foundation plan for rigid installation and the connection to the gearbox has not changed. However, for applications with resilient mounting, the use of improved dampers will further reduce engine vibrations and their transmission to the hull. Deliveries from August 2006 had the M20C
version installed, and some vessel series due for M20C installation are: four shipsets for containership gensets for Briese Schiffahrts GmbH, Germany, at the Shandong yard in China; two propulsion shipsets for a ro-pax ferry ordered by Caledonian McBrayne, UK, building at Stocznia Remontowa, Poland; and two propulsion shipsets for a Ngol Queve tanker in Gibraltar, at the Ceksan yard, Turkey.
The Kiel engine centre; MaK M 25 and M 32 C assembly. 36
Production process amended The boom in the global marine business has prompted Caterpillar Marine Power Systems to invest in its engine and component manufacturing process. The Caterpillar Production System (CPS) is being implemented with the intention of improving the quality, safety, and speed of its manufacturing systems, by standardising operations and supply chain management throughout the entire production process.
SHIP & BOAT INTERNATIONAL MAY/JUNE 2007
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