Marine engines

CM Technologies – condition monitoring on the high seas

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Skilled labour is demanded on drilling platforms, freighters, cruise or container ships If a technical fault occurs on a „factory at sea“, the crew must get to grips with it themselves. External service engineers are only available again in the next shipping port. Maximum operational safety and a comprehensive condition monitoring system are therefore particularly important at sea.

The condition of the drive units and also pumps, cranes, winches and many other systems need to be constantly monitored. In addition, the quality of the drinking water, the safety of waste water and even the cooling and boiler water must be checked.

For this range of tasks CM Technologies GmbH/ Elmshorn, known previously as Kittiwake GmbH, offers tailored solutions with online and offline monitoring systems. Depending on the system
type and operating conditions, the following technologies are combined:

  • lubrication and fuel monitoring on site using CMT rapid test devices.
  • regular analysis of specimens in the OELCHECK laboratory
  • vibration analysis for early damage detection
  • monitoring of physical parameters (speed, rotation speed, pressure, temperature and output) using sensors.

The monitoring of large marine engines is one of the core competences of CMT. Passenger and medium-sized cargo ships are often driven by fourstroke diesel engines with an output of more than 50,000 kW. By contrast, large cargo and container ships are powered with slowly running two-stroke diesel engines with a driving power of up to 10,000 kW - the rotation speeds achieve between 35 and 100 rpm. Up to 14 cylinders are installed in series. The force is transmitted directly on to the propeller. At full speed, speeds of up to 25 kn (45 km/h) are achieved. The weight of a engine of about 13 m high and 32 m long is almost 3,000 tonnes.

Two different oil types are used in a slow -running two-stroke diesel engine.

  • An SAE 50 (sometimes also SAE 40) cylinder oil IS injected directly into the individual cylinder or fed in using a central lubrication pump. It must not only lubricate but primarily it must protect the components from corrosive wear by neutralising combustion residues. Most of it is burned with the fuel. In the process large ships use 2 tonnes and more of cylinder oil per day. Remaining quantities are caught on the cylinder shroud as " drip oil" which then is analysed in the lab for the optimisation of the relubrication quantity.
  • An SAE 30 or SAE 40 system oil lubricates the connecting-rod bearings and all other moving parts of the engine using a complex circulation system. The system FOR ENGINE transmission lubrication takes a lot more than 10, 000 litres. Normally the oil is never changed completely but a partial change of a maximum of 30% always takes place depending on oil analyses.

Only monograde engine oils are used. In the process the cylinder and system oils and the oils for four-stroke marine diesel have a considerably higher alkaline reserve (BN) than oils for car or truck engines due to the combustion of high sulphur fuels.

The check of engines and power units on ships should take place as far as possible without human intervention. The monitoring of general machine condition, wear behaviour and oil situation with a single sensor is still a thing of the future. However, CMT has developed an optimal solution with its monitoring systems. The systems combine different monitoring modules in one unit. The installation near the lubricating oil system is simple. Effective distance maintenance is possible through data transfer. All online sensors from CMT can be combined in such a way that metallic abrasion and wear, the oil situation, oscillations and vibrations, temperatures and other parameters can be recorded. CMT offers an extensive service for installation, startup or repair of the condition monitoring systems. Service technicians from the company also go on board as a matter of course. In addition, there is a network of agents available at all central locations round the globe.

CMT carries out special training and seminars so that everything runs perfectly at sea. Finally, a good understanding of condition monitoring by the ship crews has a direct influence on the lifetime and reliability of the systems. The training sessions also include the subject of „Oil - the elixir of life“. In particular, the oils for marine diesel engines have extreme challenges to overcome. Normally, HFO (heavy fuel oil) is used as fuel. Its quality not only varies constantly but it is also relatively heavily polluted with water, silicon, nickel vanadium and above all sulphur. However, the engine oil of the fourstrokes and the cylinder oil of the slowly running two-strokes not only have to cope with pollution from the heavy oil but also with changing feeding rates and humidity. In order to be able to neutralise the sulphur, which can still be up to 4.5% at the moment, oils with a high base number (BN) of up to 100 are used. If the base number decreases too much, there could be damage from the aggressive effect of the acids which result from the combustion of sulphur. The CMT online sensors should recognise changes in the oil early which possibly could be indicative of a wear process or of inadequate lubrication. In order to err on the side of caution, CMT also recommends additional regular lubricant analyses. In order to be able to offer the ship customer a tailored laboratory analysis service in this area, CMT and OELCHECK have gone into partnership. They are a necessary addition particularly for trend analyses. The laboratory in Brannenburg offers more possibilities to test an oil systematically than the sensors or the rapid test method on board. The ship engineers receive comprehensive information on wear values, impurities, the oil condition, the important titrated base number and the remaining oil additives with the analysis results which have comments.

In addition, the OELCHECK tribologists make important suggestions in their comments on problems with the system or the oil. Analysing the „drip oil“ involves the influence of the heavy oil polluted with sulphur and other impurities on the cylinder oil of the large two-stroke diesel engines. Then there are, for example recommendations to check the sulphur content of the heavy oil and adjust the dosage of the cylinder lubricating oil accordingly. If the cylinders are supplied with too much oil, it can also quickly result in deposits on the piston crown as well as a greater impact on the environment and to the purse strings. Too little lubrication, however, leads to increased wear and also often to a piston seizure. Through a leak on the stuffing box of the piston rod, increased entry of cylinder oil into the circulating oil can occur. Through this, more than 10,000 litres of oil are then limited in performance in such a way that a partial exchange has to take place. Nevertheless, it is only when the oil analyses show that too much cylinder oil has gone into the circulating oil that those responsible on board have the capacity to isolate the cause of it.

OELCHECK has become an important partner of CM Technologies GmbH over the years. The analysis sets for the most diverse of usage scenarios and the tools for taking specimens are a permanent feature of CMT‘s range. Through this partnership, lubricant specimens from ports all around the world arrive almost daily at OELCHECK in Brannenburg.

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