Home » , , , » preparing the engine and pre stop and measures of ME

preparing the engine and pre stop and measures of ME

marine notes by mworld

Type: Two stroke, single acting direct reversible,
cross head diesel engine with two constant
pressure turbo chargers and air coolers.
Number of cylinders: 7
Cylinder bore: 620 mm
Stroke: 2,150 mm
Output (M.C.R.): 15540 bhp at 113 rpm
Direction of rotation: Clockwise looking from aft
Specific fuel oil consumption: 124.3 g/bhp per hour
Firing order: 1-6-3-4-5-2-7

Procedure for Preparing the Engine for Starting
Before starting the engine, the below mentioned checks and procedures must
be followed:
All components that have been overhauled should have been correctly reassembled
and fitted and their function checked.
All devices and tools, which were used, have been removed from the engine
and that no cleaning rags or other items have been left behind.
a) Check the fluid levels of all the tanks in the engine systems
(including the leakage drain tanks).
b) Check that all the shut-offs for the engine cooling water and
lubricating oil systems are in the correct position.
c) Open the air supply to the shipboard system and from the starting
air receivers to the control air supply.
d) Prepare the fuel.
e) Start up the pumps for cylinder cooling water, bearing and crosshead
bearing lubricating oil and set the pressures to their normal
values.
f) Check to ensure that all system vents are open.
g) Open each cylinder head indicator cock. Using the turning gear,
turn the engine through a minimum of one full revolution to check
that all the running gear is in order. Check if any large quantities
of water, oil or fuel has collected on the piston crown. Operate the
cylinder pre-lubrication system.
h) Shut the indicator valves.
i) Check to ensure that all the crankcase doors are closed with all the
latches tight.
j) Check to ensure that cutting out devices for all the fuel injection
pumps are correctly positioned.
k) Check that the fuel regulating linkage moves freely.
l) Check the pressure in the starting air receivers and open their
drains until any condensate has been drained.
m) Open the drain and test valves AE035 and AE036 until all water
has been drained.
n) Close venting valve AE007 and open the main shut-off valves
AE003V and AE004 on the starting air receivers.
o) The pressure gauges should now indicate the following pressures:
Safety control air and stand by supply for air spring air on
the pressure reducing valve 23HA (6 kg/cm2)
Air spring air supply on the pressure reducing valve 19HA
(7.5 kg/cm2)
Control air stand by supply on the pressure reducing valve
19HB (7 kg/cm2)
p) Set the switch at the control panel for the auxiliary blower to
AUTOMATIC.
q) Bring the safety cut-out to operating position.
r) Press the EMERGENCY STOP button on the control panel and
observe if the safety cut-out on the fuel injection pumps reacts,
i.e. their suction valves are lifted. After this check, press the
EMERGENCY STOP RESET button.
s) Check whether the pressure gauge on the supply unit for cylinder
lubrication indicates 40 kg/cm2.
t) Take out the turning gear and secure the lever.
u) Open the check cock 2.06 of the main automatic starting air shutoff
valve 2.04 for a short time and listen for the valve opening
(can be heard distinctly). Close the cock again.
v) Check hydraulic system of exhaust valve drive for tightness.
w) The levers on the local manoeuvring stand must be put into the
correct position the corresponding to where the engine will be
started, (the bridge, the control room or the auxiliary local stand).
The changeover buttons of the remote control must be activated.
x) Check again to ensure that no personnel are near the flywheel.
y) Inform the bridge.

Procedure for the Operation of the Main Engine
Slow Turning
a) Turn by the turning gear. The crankshaft can be turned at a slow
rate using the turning gear.
b) Slow turning with starting air. The running gear can be turned at
about 12 rpm by releasing the starting air by a measured amount.
This is initiated from the control room.
The following conditions must be fulfiled before activating the slow turning
operation:
Turning gear is disengaged.
Oil pumps are operating (bearing oil and cross-head oil).
Fuel interlock not released. Reversing lever is set on REMOTE
CONTROL.
Speed control on minimum (Pos. ‘0’).
Indicator valves closed.
Shut-off valves on the starting air receivers open.
Air pressure for air spring correctly set.
During slow turning, the cylinder lubrication must be switched on.

Procedure for Operating the Main Engine
It is preferable to operate the engine at constant power. When the speed / load
has to be altered, it should be done as slowly as possible.
During normal running, regular checks have to be made and precautions taken
which contribute towards trouble free operation. The most important of these
are:
a) Regular checks of pressures and temperatures.
b) The values read off the instruments compared with those given in
the acceptance records and taking into account engine speed
and/or engine power, provide an excellent yardstick for the engine
performance. Compare temperatures by feeling the pipes.
The essential readings are: The load indicator position, turbo-charger speed,
charge air pressure, exhaust gas temperature before the turbine. A valuable
criterion is also the daily fuel consumption, considering the lower calorific
value.
c) Check all shut-off valves in the cooling and lubricating system for
their correct position. The shut-offs for the cooling inlets and
outlets on the engine must always be fully open in service. These
serve only to cut off individual cylinders from the cooling water
circuit during overhauls.
d) When abnormally high or low temperatures are detected at a
water outlet, the temperature must be brought to the prescribed
normal value very gradually. Abrupt temperature changes may
cause damage.
e) The maximum permissible exhaust temperature at turbine inlet
must not be exceeded.
f) Check combustion by observing the colour of the exhaust gases.
g) Maintain the correct charge air temperature after the air cooler
with the normal water flow. In principle, higher charge air
temperature will result in poorer filling of the cylinder, which in
return will result in a higher fuel consumption and higher exhaust
gas temperatures.
h) Check the charge air pressure-drop through the air filter and air
cooler. Excessive resistance will lead to a lack of air to the engine.
i) The fuel oil has to be carefully cleaned before being used. Open
the drain cocks of all fuel tanks and fuel oil filters regularly for a
short period to drain off any water or sludge, which may have
collected there. Maintain the correct fuel oil pressure at the inlet
to the fuel injection pumps. Adjust the pressure at the injection
pump inlet with the pressure-regulating valve in the fuel oil return
pipe so that the fuel oil circulates within the system at the normal
delivery capacity of the booster pump.
j) The heavy fuel oil has to be sufficiently heated to ensure that its
viscosity before inlet to the fuel injection pumps lies within the
prescribed limits.
k) Determine the cylinder lubricating oil consumption. Extended
service experience will determine the optimum cylinder
lubricating oil consumption.
l) The cooling water pumps should be run at their normal operating
-point, i.e. the actual delivery head corresponds with the designed
value. If the temperature difference between inlet and outlet
exceeds the desired value, pump overhaul should be considered.
m) The vents at the uppermost points of the cooling water spaces
must be kept closed.
n) Check the level in all water and oil tanks, as well as all the
drainage tanks of the leakage piping. Investigate any abnormal
changes.
o) Observe the condition of the cooling water. Check for oil contamination.
p) Check the charge air receiver drain manifolds sight glass to see if
any water is draining away and if so, how much.
q) Drain the scavenge spaces. To do this, open the drain cock of the
leakage manifold daily and look to see if any liquid flows out
along with the charge air.
r) Check the pressure drop across the oil filters. Clean them if
necessary.
s) The temperature of the running gear should be checked by feeling
the crankcase doors. Bearings, which have been overhauled or
replaced, must be given special attention for some time after
being put into service.
t) Listening to the noise of the engine will reveal any irregularities.
u) Hand drawn indicator diagrams and Premet XL data provide
information on the combustion process and pressures within the
cylinder. When the quality of the fuel used changes the maximum
pressure in the cylinder at service power must be determined at
the earliest opportunity and compared with the pressure measured
during the corresponding ship trial (speed, power).
v) Centrifuge the lubricating oil. Samples should be taken at regular
intervals.
w) Replenish the air cushion in damping vessels of fuel oil system.
x) Check the inspection glasses in the upper casing of the exhaust
valve periodically and note if the air spring cylinder of each
exhaust valve is rotating. If not, the offending valve must be
overhauled at the next opportunity.

Procedures after Shutting Down the Engine
After the engine has been stopped, the cooling water and lubricating oil pumps
should be left running for at least a further 20 minutes in order to allow the
temperatures to equalise. These systems should not be cooled down below
their normal inlet temperatures.
The starting air supply has to be closed as soon as possible after stopping the
engine i.e. shut the valves AE004V and AE005V on the starting air receivers
and open the venting valve AE007V.
The indicator cocks in the cylinder heads are to be opened and the turning gear
engaged.
Post-lubrication of the cylinders:
For the post-lubrication of the cylinders, the crankshaft must be turned by the
turning gear. During this the cylinder lubrication (push-button for ‘postlubrication’)
must also be switched on for the same period.
a) Close the shut-off valves from the starting air receivers.
b) Where possible, keep the cooling water warm in order to prevent
the engine from cooling down too much. The jacket cooling water
pump should be kept running unless required to be stopped for
maintenance work.
c) Turn the engine, at intervals, through several revolutions with the
indicator cocks open, using the turning gear, (possibly done daily
in damp climates). Do this with the lubricating oil pump running
and operating the cylinder lubricating pumps at the same time.
After completing this procedure, ensure that the pistons come to
rest in a different position each time.
d) Repair all the defects detected in service (leaks, etc.).
e) Follow all the safety regulations when carrying out repair work or
any overhauls which are due.

Fouling and fires in the scavenge air spaces.
The principle cause of fouling is blow-by of combustion products between
piston and cylinder into the scavenge air spaces. The fouling will be greater if
there is incomplete combustion of the fuel injected (smokey exhaust).
Causes of poor combustion:
The fuel injectors are not working correctly.
The fuel is at too low a temperature.
Poorly adjusted injection pump timing.
Operation with a temporary shortage of air during extreme variations
in engine loading and with the charge air pressure dependent fuel
limiter in the governor set too high.
Overloading.
Insufficient supply of air due to restricted engine room ventilation.
Fouling of the air intake filters and diffuser on the air side of the turbo-charger.
Fouling of the exhaust gas boiler, the air cooler, the air flaps in the
charge air receiver and of the scavenge ports.
Causes of blow-by of combustion products:
Worn, sticking or broken piston rings.
Individual cylinder lubricating quills are not working.
Damage to the running surface of the cylinder liners.
If one or more of these operating conditions prevail, residues, mainly
consisting of incompletely burnt fuel and cylinder lubricating oil, will
accumulate at the following points:
Between piston rings and piston ring grooves.
On the piston skirts.
In the scavenge ports.
On the bottom of the cylinder jacket (piston underside).
Causes of the fires:
The blow-by of hot combustion gases, and sparks which have
bypassed the piston rings between piston and cylinder liner running
surface, enter the space on the piston underside.
Any residues present can ignite.
Indications of a fire:
Sounding of the respective temperature alarms if the engine has the
necessary monitoring instrumentation installed.
A considerable rise in the exhaust gas temperatures of the cylinder
concerned and a general rise in charge air temperature.
The turbo-charger may start surging.
Fire fighting measures:
Reduce engine power.
Cut out the fuel injection pump of the cylinder concerned.
Increase lubrication to the respective cylinder.
(If a serious fire occurs shut down the engine and operate the fixed fire
extinguishing system.)
A fire should have died down after 5 to 15 minutes. This can be
verified by checking the temperatures of the exhaust gas and the doors
to the piston bottoms.
Afterwards the engine must be stopped as soon as possible and the
cause of the fire established.
Checks should include:
Cylinder liner running surface, piston and piston rings, air flaps in the
receiver (to be replaced if necessary), possible leakages, piston rod
gland, fuel injection nozzles.
After a careful check or if necessary repair, the engine can be put back
on load with cut-in fuel injection pump and automatic cylinder
lubrication.
Should a stoppage of the engine not be feasible and the fire has died
down, the fuel injection pump can again be cut in, the load increased
slowly and the cylinder lubrication brought back again to the normal
output. Avoid running for hours with considerably increased cylinder
lubrication.
Preventive measures
As can be seen from the causes, the following engine maintenance goes a long
way to safeguarding against fires in the scavenge air spaces:
Use of correctly spraying fuel injectors and keeping the air and gas
passages clean.
Optimum adjustment of the fuel cams and of the fuel injection pump
timing.
When running continuously at reduced load, check the cylinder
lubricating oil feed rate and readjust if necessary.
The permanent drain of residue from the piston underside must always
be checked. To prevent accumulation of dirt, the drain cock on the
collector main must be opened for a short time each day.
Prevention of crankcase explosions
The oil mist in the crankcase is inflammable over a very narrow range of
mixture. Weaker or richer mixtures do not fire. There must always be an
extraneous cause to set off ignition, such as hot engine components. Only
under these circumstances and the presence of a critical mixture ratio of oil
mist and air can an explosion occur.
Engines are equipped with an oil mist detector, which constantly monitors
intensity of oil mist in the crankcase and triggers an alarm if the mist exceeds
the density limit.
Measures to be taken when Oil Mist has occurred
a) Do not stand near crankcase doors or relief valves or in corridors
near doors to the engine room casing.
b) Reduce speed to slow-down level, if not already carried out automatically.
Ask the bridge for permission to stop.
c) When the engine STOP order is received: Stop the engine.Close
the fuel oil supply.
d) Switch-off the auxiliary blowers.
e) Open the skylight(s) and / or ‘stores hatch’.
f) Leave the engine room.
g) Lock the casing doors and keep away from them.
h) Prepare the fire-fighting equipment.
i) Do not open the crankcase until at least 20 minutes after stopping
the engine. When opening up, keep clear of possible spurts of
flame. Do not use naked lights and do not smoke.
j) Stop the lubricating oil pump. Take off/open all the lower most
doors on one side of the crankcase. Cut off the starting air, and
engage the turning gear.
k) Locate the ‘hot spot’. Feel over, by hand all the sliding surfaces
(bearings, thrust bearing, piston rods, stuffing boxes, cross-heads,
telescopic pipes, chains, vibration dampers, moment compensators,
etc.). Look for squeezed-out bearing metal, and discolouration
caused by heat (blistered paint, burnt oil, oxidised
steel). Keep possible bearing metal found at bottom of oil tray for
later analysing. Prevent further ‘hot spots’ by preferably making
a permanent repair. Ensure that the respective sliding surfaces are
in good condition. Take special care to check that the circulating
oil supply is in order.
l) Start the circulating oil pump and turn the engine by means of the
turning gear. Check the oil flow from all bearings, spray pipes and
spray nozzles in the crankcase, chain-case and thrust bearing.
Check for possible leakages from pistons or piston rods.
m) Start the engine. After running for about 30 minutes. Stop and feel
over. Look for oil mist. Especially feel over the sliding surfaces,
which caused the overheating. There is a possibility that the oil
mist is due to:
‘Atomisation’ of the circulating oil, caused by a jet of air / gas.
Stuffing box leakages (not air tight).
Blow-by through a cracked piston crown or piston rod (with
direct connection to crankcase via the cooling oil outlet pipe).
An oil mist could also develop as a result of heat from a
scavenge fire being transmitted down the piston rod or via the
stuffing box.
Hot air jets or flames could also have passed through the
stuffing box into the crankcase.

??.:: Request Your Doubts Here ::.??

Telugu Songs Online .::MK::. Telugu Songs Online
Facebook:Marine NotesTwitter:ACMWCTRss:ACMWCT
Marine Notes - MMD Exams India and Baiscs
URL: HTML link code: BB (forum) link code:
© Marine Notes - MMD Exams India and Basics (M&K Groups Ltd)

0 comments:

Facebook Marine Notes
Twitter Marine Notes
Rss Marine Notes

Followers

Follow by Email