7 семестр (Бормотов А) / 1man_bw_l23_30_chn_23_30_instruktsiya_po_ekspluatatsii / MAN-BW L23-30 (ЧН 225_300)+ / MAN-BW L23-30 H Vol-1 (Instruction)+

08028-0D/H5250/94.08.12

Performance Data and Engine Condition

During operation small alterations of the engine condition continuously take place as a result of combustion,includingfoulingofairwaysandgasways, formation of deposits, wear, corrosion, etc. If continuously recorded, these alterations of the condition can give valuable information about the operational and maintenance condition of the engine. Continual observations can contribute to forming a precise and valuable basis for evaluation of the optimal operation and maintenance programmes for the individual plant.

We recommend taking weekly records of the most importantperformancedataoftheengineplant.During recording (working card 502-01.00 can be used), the observations are to be continually compared in order to ascertain alterations at an early stage and before theseexertanyappreciableinfluenceontheoperation of the plant.

Asareferenceconditionfortheperformancedata,the testbed measurements of the engine or possibly the measurementstakenduringtheseatrialatthedelivery of the ship can be used. If considerable deviations from the normal condition are observed, it will, in a majority of cases, be possible to diagnose the cause of such deviations by means of a total evaluation and a set of measurements, after which possible adjustment/overhauls can be decided and planned.

Evaluation of Performance Data

For example, fouling of the air side of the air cooler will manifest itself in an increasing pressure drop, lower charge air pressure and an increased exhaust temperature level (with consequential influence on the overhaul intervals for the exhaust valves).

Fouling of the turbine side of the turbocharger will, in itsfirstphase,manifestitselfinincreasingturbocharger revolutions on account of increased gas velocity throughthenarrowednozzleringarea.Inthelongrun, the charging air quantity will decrease on account of the greater flow resistance through the nozzle ring, resultinginhigherwalltemperaturesinthecombustion chambers.

L23/30H

V28/32S

An increase of charge air temperature involves a correspondingincreaseoftheexhaustgastemperature level in a ratio of about 1:1.5, i.e. 1°C higher charge air temperature causes about 1.5°C higher exhaust gas temperature.

Reduction of the charge air pressure results in a corresponding reductionofthecompressionpressure and max. combustion pressure. When checking the max.pressureadjustmentoftheengine,itistherefore to be ensured that the existing charge air pressure is correct.

The injected amount of fuel is equivalent to supplied energyandisthusanexpressionoftheloadandmean pressure of the engine. The fuel pump index can therefore be assumed to be proportional to the mean pressure. Consequently, it can be assumed that the connected values of the pump index are proportional to the load.

The specific fuel consumption, SFOC (measured by weight) will, on the whole, remain unaltered whether the engine is operating on HFO or on MDO, when considering the difference in calorimetric combustion value. However, when operation on HFO, the combination of density and calorific value may result in an alteration of up to 6% in the volumetric consumption at a given load. This will result in a corresponding alteration in the fuel pump index, and regard should be paid to this when adjusting the overload preventative device of the engine.

Abrasive particles in the fuel oil result in wear of fuel pumps and fuel valve nozzles. Effective treatment of the fuel oil in the purifier can limit the content of abrasiveparticlestoaminimum.Wornfuelpumpswill result in an increase of the index on account of an increased loss in the pumps due to leakage.

When evaluating operational results, a distinction is tobemadebetweenalterationswhichaffectthewhole engine (all cylinder units) and alterations which occur in only one or a few cylinders. Deviations occuring for afewcylindersare,asarule,causedbymalfunctioning of individual components, for example, a fuel valve with a too low opening pressure, blocked nozzle holes, wear, or other defects, an inlet or exhaust valve with wrongly adjusted clearance, burned valve seat etc.

The operational observations supplemented by the daily routine monitoring contribute to ensuring that faulty adjustments and other deviations in the performance of individual components are observed in time to avoid operational disturbances and so that normal routine overhauls can be carried out as scheduled.

If abnormal or incomprehensible deviations in the operation are recorded, expert assistance for the evaluation of these should be obtained.

Turbochargers

Service experience has shown that the turbine side is exposedtoincreasedfoulingwhenoperatingonHFO.

The rate of fouling and thereby the influence on the operation of the engine is greatest for small turbochargers where the flow openings between the guide vanes of the nozzle ring are relatively small. Deposits especially occur on the guide vanes of the nozzle ring and on the rotor blades. In the long run, fouling will reduce the efficiency of the turbocharger and thereby also the quantity of air supplied for the combustion of the engine. A reduced quantity of air willresultinhigherwalltemperaturesinthecombustion spaces of the engine.

Detailedinformationandinstructionsregardingwater washing of the turbocharger are given in the section 512.

Fuel Valves

Assuming that the fuel oil is effectively purified and that the engine is well maintained, the operational conditionsforthefuelvalvesandtheoverhaulintervals willnotnormallybeessentiallyalteredwhenoperating on HFO.

If, for any reason, the surface temperature of the fuel valve nozzle is lower than the condensation temperature of sulphuric acid, sulphuric acid condensate can form and corrosion take place (cold corrosion). The formation of sulphuric acid further depends on the sulphur content in the fuel oil.

Normally, the fuel nozzle temperature will be higher than the approx. 180°C, at which cold corrosion starts to occur.

Abrasiveparticlesinthefueloilinvolveaheavierwear of the fuel valve needle, seat, and fuel nozzle holes. Therefore, abrasive particles are, to the greatest possible extent, to be removed at the purification.

Exhaust Valves

The overhaul intervals of exhaust valves is one of the key parameters when reliability of the entire engine is to be judged. Operation on HFO has a negative effect on these intervals. The performance of the exhaust valves is therefore extremely informative.

Especially under favourable conditions, fuel qualities withahighvanadiumandsodiumcontentwillpromote burningofthevalveseats.Combinationsofvanadium and sodium oxides with a corrosive effect will be formed during the combustion. This adhesive ash may, especially in the case of increased valve temperatures, form deposits on the seats. An increasing sodium content will reduce the melting point and thereby the adhesive temperature for the ash, which will involve a greater risk for deposits. This condition will be especially unfavourable when the weight ratio Na increases beyond 1:3.

Va

Theexhaustvalvetemperaturedependsontheactual maintenance condition and the load of the engine. With correct maintenance, the valve temperature is kept at a satisfactory low level at all loads. The air supply to the engine (turbocharger/air cooler) and the maximumpressureadjustmentarekeyparametersin this connection.

It is important for the functioning of the valves that the valve seats are overhauled correctly in accordance with our instructions.

The use of rotocaps ensures a uniform distribution of temperature on the valves.

08028-0D/H5250/94.08.12

Air Inlet Valves

The operational conditions of the air inlet valves are not substantially altered when using residual fuel.

Fuel Pumps

Assuming effective purification of the fuel oil, the operation of the fuel pumps will not be very much affected.

Theoccurrenceofincreasingabrasivewearofplunger and barrel can be a consequence of insufficient purification of the fuel oil, especially if using a fuel which contains residues from catalytic cracking. Water in the fuel oil involves an increased risk of cavitation in connection with pressure impulses occurring at the cutting-off of the fuel pump. A fuel withahighasphaltcontenthasdeterioratinglubricating propertiesandcan,inextremecases,resultinsticking of the fuel pump plungers.

L23/30H

V28/32S

Engine Room Ventilation, Exhaust System

Good ventilation of the engine room and a suitable location of the fresh air intake on the deck are important. Seawater in the intake air might involve corrosive attack and influence the overhaul intervals for the exhaust valves.

The fresh air supply(ventilation) to the engine room is to correspond to approximately 1.5 times the air consumption of the engines and possible boilers in operation.Sub-pressureintheengineroomwillinvolve an increased exhaust temperature level.

The exhaust back-pressure measured after the turbochargers at full load should not exceed 250-300 mm water gauge. An increase of the exhaust backpressure will also involve an increased exhaust valve temperature level.

08028-0D/H5250/94.08.12

ALL CYLINDERS Exhaust temp. increasing: Air system fouled

(Air filter-blower-cooler). Exhaust system fouled (nozzle ring, turbine wheel).

ONE CYLINDER Exhaust temp. in-

creasing: Fuel valve needs overhaul. Compression too low owing to leakage of exhaust valve or piston ring blow-by.

Pcomp and Pmax are measured by means of max. pressure gauge.

Pcomp too low: Leaky combustion chamber, charging air pressure too low.

Pmax too low:

P comp too low, ignition too late.

L23/30H

PRESSURE DROP INCREASING (limit 50%)

Air filters fouled.

PRESSURE DROP INCREASING (limit 50%)

Air side of cooler fouled.

TEMP. DIFFERENCE

TOO LARGE

Water flow too small

T

T

TEMP. DIFFERENCE

TOO LARGE

Air cooler fouled.

DECREASING CHARGE AIR PRESSURE:

Decreasing air amount. Fouled turbocharger, air filter or charge

air cooler (air side).

See also:

Engine Performance and condition 501.01

08028-0D/H5250/94.08.12

General

There is always a certain amount of water in air. When the air is saturated with aqueous vapour, the humidity is said to be 100% and there is as much water in the air as it can absorb without condensing. The amount of water in kg/kg air can be found from the diagram. The ability to absorb water depends on the pressure and temperature of the air.

Amount of Condensation Water in the Charge

Air Receiver

Both higher pressure and lower temperature reduce the ability to absorb water. A turbocharged diesel engine takes air from outside, compresses and cools the air.

Then normally, the air cannot absorb the same amount of water as before.

Condensation of water in the engine's charge air receiver is consequently dependent on the humidity and the temperature of the ambient air. To find out if condensation in the charge air receiver will occur the diagram can be used.

Example:

General

As a guidance, an air consumption of 8.2 kg/kWh (Le) at full load can be used for MAN B&W, Holeby engines.

Solution according to diagram:

Amount of condensate in charge air receiver.

Draining of Condensation Water

This phenomenon will occur on all turbocharged engines. For MAN B&W, Holeby 4-stroke engine, there is no risk with a small amount of water in the charge air receiver. But if the charge air receiver is filled with water, there is a risk of getting water into the cylinder. This water have to be drained away. As standard a valve is mounted on the charge air receiver/cooler on the engine. This valve is to be used for draining of the water. If there is a great amount, the valve can be left half-open. If the amount is small, the charge air receiver can be drained periodically.

Amount of Condensate Water in Air Tanks

Thevolumeofcondensateintheairtankisdetermined by means of the curve at the bottom to the right of the diagram, representing an operating pressure of 30 bar.

Example:

Amount of condensate in air tank.

08028-0D/H5250/94.08.12

L23/30H

Measuring of engine performance data.

Starting position:

Engine is running.

Related procedure:

08028-0D/H5250/94.08.12

Instruction for Filling in the Diagram "Engine Performance Data"

The numbers in the instruction are commensurate with the numbers in the diagram.

The automatic symbols mentioned in the instruction (TI 01, TI 03, PI 01 etc) refer to the diagrams printed in the instruction books for specified plants and page 500.20.

Engine Performance Data

1.Name of ship, if stationary name of plant.

2.Engine type.

3.Engine No.

4.Date/year of observations.

5.Hour, time of observations.

6.Total engine running hours - engineer's log-

book.

7.Engine revolutions per minute (RPM) - can be read on tachometer SI 90.

8.Fuel oil type: the viscosity must be stated (in cSt) and the temperature by which the viscosity has been measured, f.inst. 180 cSt/50°C. Density must be stated: g/cm³.

9.Turbocharger: type and serial number are stated on the rating plate of turbocharger and page 500.00.

10.Turbocharger revolutions per minute (RPM) - can be read on the tachometer SI 89.

Switchboard.

11.Alternator output (kW) - can be read on the main switchboard.

12.Voltage (V) - can be read on the switchboard.

13.Current (A) - can be read on the switchboard.

L23/30H

14.Cos j/kVAr - can be read on the switchboard.

Cylinder Data

15.Cylinder No. - can be read on engine plate. A/B is used for V-engines.

16.Average for all engine cylinders for point: 17- 18-19-20-21.

17.Fuel pump index - can be read on each of the high pressure fuel oil injection pumps.

18.Max pressure (bar) can be read for each cylinder by means of indicator or Pmax gauge.

19.Compression pressure (bar) - can be read for each cylinder by means of the indicator measurement, which is carried out during idling by nominal RPM.

20.Exhaust temperature (°C)

-thermometer TI 60.

21.Water outlet cylinder (°C) (jacket cooling)

-thermometer TI 11.

Turbocharger

22.Thermometer inlet blower (°C) can be read by means of a thermometer placed in the engine room near the air filter of the TC.

23.Pressure before blower (mmWC) - can be read by means of a mmWC instrument placed in the engine room near the TC.

24.Temperature after blower (°C) - can be read by means of a thermometer TI 30.

25.D Pressure air cooler (mm/WC).

26.Charge air temperature (°C). Temperature of the charge air in the charge air receiver.

-thermometer TI 31.

27.Pressure charge air (bar). Pressure of the charge air in the charge air receiver.

-pressure gauge PI 31.

28.Gas before temperature exhaust TC (°C)

-thermometer TI 62.

29.Exhaust gas temperature after TC (°C)

-thermometer TI 61.

30.Exhaust gas pressure after the TC (bar)

-pressure gauge PI 61.

Lubricating Oil System

31.Lub. oil inlet cooler temperature (°C)

-thermometer TI 20.

32.Lub. oil pressure before the filter (bar)

-pressure gauge PI 21.

33.Pressure of the lub. oil after the filter (bar)

-Pressure gauge PI 22.

The filter element should be replaced with a pressure drop across the filter of 1.5 bar (see section 615).

34.Lub. oil inlet engine temperature (°C)

-thermometer TI 22.

35.Lub. oil pressure before the turbocharger

(bar).

-pressure gauge PI 23.

Cooling Water System

37.Low temperature (LT) cooling water temperature (sea, raw or fresh) at inlet charge air cooler (°C)

-thermometer TI 01.

38.Low temperature (LT) cooling water temperature (sea, raw or fresh) at outlet charge air cooler (°C)

-thermometer TI 02.

39.Low temperature (LT) cooling water pressure (sea, raw or fresh) at inlet charge air cooler (bar)

-pressure gauge PI 01.

40.Low temperature (LT) cooling water tempera-

ture (sea, raw or fresh) at inlet lub. oil cooler (°C)

-thermometer TI 07.

41.Low temperature (LT) cooling water temperature (sea, raw or fresh) at outlet lub. oil cooler °C)

-thermometer TI 03.

42.Low temperature (LT) cooling water temperature (sea, raw or fresh) at inlet alternator (°C)

-thermometer TI 04.

43.Low temperature (LT) cooling water temperature (sea, raw or fresh) at outlet alternator (°C)

-thermometer TI 05.

44.High temperature (HT) fresh water temperature (FW) at inlet engine (°C)

-thermometer TI 10.

45.High temperature (HT) fresh water temperature (FW) of outlet engine (°C)

-thermometer TI 10.

Fuel Oil System

46.Fuel oil temperature at inlet engine (°C)

-thermometer TI 40.

47.Fuel oil pressure before engine (bar)

-pressure gauge PI 40.

48.

49.

50.Signature.

08028-0D/H5250/94.08.12