s90mec7

Jacket water cooling pump

The pumps are to be of the centrifugal type.

Working temperature,.............. 80 °C, max. 100 °C The capacity must be met at a tolerance of 0% to +10%.

The stated capacities cover the main engine only. The pump head of the pumps is to be determined based on the total actual pressure drop across the cooling water system.

Freshwater generator

If a generator is installed in the ship for production of freshwater by utilising the heat in the jacket water cooling system it should be noted that the actual available heat in the jacket water system is lower than indicated by the heat dissipation figures given in the ‘List of capacities.‘ This is because the latter figures are used for dimensioning the jacket water cooler and hence incorporate a safety margin which can be needed when the engine is operating under conditions such as, e.g. overload. Normally, this margin is 10% at nominal MCR.

The calculation of the heat actually available at specified MCR for a derated diesel engine is stated in chapter 6 ‘List of capacities‘.

For illustration of installation of fresh water generator see Fig. 12.05.01.

Jacket water thermostatic valve

The temperature control system is equipped with a three way valve mounted as a diverting valve, which by pass all or part of the jacket water around the jacket water cooler.

The sensor is to be located at the outlet from the main engine, and the temperature level must be adjustable in the range of 70 90 °C.

Jacket water preheater

When a preheater, see Fig. 12.05.01, is installed in the jacket cooling water system, its water flow, and thus the preheater pump capacity, should be about 10% of the jacket water main pump capacity.

Based on experience, it is recommended that the pressure drop across the preheater should be approx. 0.2 bar. The preheater pump and main pump should be electrically interlocked to avoid the risk of simultaneous operation.

The preheater capacity depends on the required preheating time and the required temperature increase of the engine jacket water. The temperature and time relations are shown in Fig. 12.08.01.

In general, a temperature increase of about 35 °C (from 15 °C to 50 °C) is required, and a preheating time of 12 hours requires a preheater capacity of about 1% of the engine`s nominal MCR power.

Deaerating tank

Design and dimensions of the deaerating tank are shown in Fig. 12.07.01 ‘Deaerating tank‘ and the corresponding alarm device is shown in Fig. 12.07.02 ‘Deaerating tank, alarm device‘.

Expansion tank

The total expansion tank volume has to be approximate 10% of the total jacket cooling water amount in the system.

Fresh water treatment

The MAN Diesel recommendations for treatment of the jacket water/freshwater are available on request.

MAN B&W MC/MC C, ME/ME-B/ME C/ME GI engines

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Deaerating tank dimensions

ND: Nominal diameter

Working pressure is according to actual piping arrangement.

In order not to impede the rotation of water, the pipe connection must end flush with the tank, so that no internal edges are protruding.

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MAN B&W K98MC/MC-C6/7, K98ME/ME C6/7, S90MC-C7/8, S90ME C7/8, K90MC-C6, K90ME9, K90ME C6/9, S80MC6, K80MC-C6, K80ME C6/9

Temperature at Start of Engine

In order to protect the engine, some minimum temperature restrictions have to be considered before starting the engine and, in order to avoid corrosive attacks on the cylinder liners during starting.

Normal start of engine

Normally, a minimum engine jacket water temperature of 50 °C is recommended before the engine is started and run up gradually to 90% of specified MCR speed.

For running between 90% and 100% of specified MCR speed, it is recommended that the load be increased slowly – i.e. over a period of 30 minutes.

Start of cold engine

In exceptional circumstances where it is not possible to comply with the above-mentioned recommendation, a minimum of 20 °C can be accepted before the engine is started and run up slowly to 90% of specified MCR speed.

However, before exceeding 90% specified MCR speed, a minimum engine temperature of 50 °C should be obtained and, increased slowly – i.e. over a period of at least 30 minutes.

The time period required for increasing the jacket water temperature from 20 °C to 50 °C will depend on the amount of water in the jacket cooling water system, and the engine load.

Note:

The above considerations are based on the assumption that the engine has already been well run in.

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Fig. 12.08.01: Jacket water preheater

Preheating of diesel engine

Preheating during standstill periods

During short stays in port (i.e. less than 4 5 days), it is recommended that the engine is kept preheated, the purpose being to prevent temperature variation in the engine structure and corresponding variation in thermal expansions and possible leakages.

The jacket cooling water outlet temperature should be kept as high as possible and should – before starting up – be increased to at least 50 °C, either by means of cooling water from the auxiliary engines, or by means of a built in preheater in the jacket cooling water system, or a combination.

MAN B&W MC/MC C, ME/ME-B/ME C/ME GI engines

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The starting air of 30 bar is supplied by the starting air compressors (4 50 602) to the starting air receivers (4 50 615) and from these to the main engine inlet ‘A’.

Through a reducing station (4 50 665), compressed air at 7 bar is supplied to the control air for exhaust valve air springs, through ‘B’.

Through a reducing valve (4 50 675) is supplied compressed air at 10 bar to ‘AP’ for turbocharger cleaning (soft blast) , and a minor volume used for the fuel valve testing unit.

Starting air and control air for the GenSets can be supplied from the same starting air receivers, as for the main engine.

Please note that the air consumption for control air, safety air, turbocharger cleaning, sealing air for exhaust valve and for fuel valve testing unit are momentary requirements of the consumers.

For information about a common starting air system for main engines and MAN Diesel auxiliary engines, please refer to our publication:

Uni concept Auxiliary Systems for Two stroke Main

The publication is available at www.mandiesel.com under ‘Quicklinks’ → ‘Technical Papers’

MAN B&W S90ME C7, K90ME C6

Components for Starting Air System

Starting air compressors

The starting air compressors are to be of the water cooled, two stage type with intercooling.

More than two compressors may be installed to supply the total capacity stated.

Starting air receivers

The volume of the two receivers is:

* The volume stated is at 25 °C and 1,000 mbar

Reduction station for control and safety air

In normal operating, each of the two lines supplies one engine inlet. During maintenance, three isolating valves in the reduction station allow one of the two lines to be shut down while the other line supplies both engine inlets, see Fig. 13.01.01.

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Reduction valve for turbocharger cleaning etc

The consumption of compressed air for control air, exhaust valve air springs and safety air as well as air for turbocharger cleaning and fuel valve testing is covered by the capacities stated for air receivers and compressors in the list of capacities.

Starting and control air pipes

The piping delivered with and fitted onto the main engine is shown in the following figures in Section 13.03:

Fig. 13.03.01 Starting air pipes

Fig. 13.03.02 Air spring pipes, exhaust valves

Turning gear

The turning wheel has cylindrical teeth and is fitted to the thrust shaft. The turning wheel is driven by a pinion on the terminal shaft of the turning gear, which is mounted on the bedplate.

Engagement and disengagement of the turning gear is effected by displacing the pinion and terminal shaft axially. To prevent the main engine from starting when the turning gear is engaged, the turning gear is equipped with a safety arrangement which interlocks with the starting air system.

The turning gear is driven by an electric motor with a built in gear and brake. Key specifications of the electric motor and brake are stated in Section 13.04.

MAN B&W ME/ME C/ME GI, S50ME-B8/9

The starting air pipes, Fig. 13.03.01, contain a main starting valve (a ball valve with actuator), a non return valve, a solenoid valve and a starting valve. The main starting valve is controlled by the Engine Control System. Slow turning before start of engine (4 50 140) is included in the basic design.

The Engine Control System regulates the supply of control air to the starting valves in accordance with the correct firing sequence and the timing.

Please note that the air consumption for control air, turbocharger cleaning and for fuel valve testing unit are momentary requirements of the consumers. The capacities stated for the air receivers

and compressors in the ‘List of Capacities’ cover all the main engine requirements and starting of the auxiliary engines.

For information about a common starting air system for main engines and auxiliary engines, please refer to the Engine Selection Guide or to our publication:

Uni concept Auxiliary Systems for Two stroke Main

The publication is available at www.mandiesel.com under ‘Quicklinks’ → ‘Technical Papers’

MAN B&W ME/ME C/ME GI engines

The exhaust valve is opened hydraulically by the Fuel Injection Valve Actuator (FIVA) system which is activated by the Engine Control System, and the closing force is provided by an ‘air spring’ which leaves the valve spindle free to rotate.

The compressed air is taken from the control air supply, see Fig. 13.03.02.

MAN B&W ME/ME C/ME GI engines