Auxiliary Systems Flashcards
Usual pressure in a deaerator?
0.5 bar
What is the purpose of a de-aerator?
Removing trapped oxygen and CO2, as they can lead to corrosion and hinder heat transfer as the heat transfer coefficient of air is less than water.
Where would the deaerator be located?
At the hottest point in the system, where the water leaves the heater or enters the cooler.
This is to give the gas more kinetic energy to allow for quicker release.
What are the causes of a starting air line explosion on ships?
1) Leaking start air valve or jamming at open position.
2) Oil discharged from compressor may deposit a thin film on the internal surfaces of the pipes but not ready for combustion.
3) Hot gas or flame may enter the manifold, vaporise the oil and set fire.
4) High pressure start air coming into contact with this may cause an explosion.
How would you prevent a start air explosion?
1) Regular overhaul and maintenance of starting air valve.
2) Test air start valve leakage.
3) Regularly drain off the air bottles.
4) Regularly drain off the air start system.
5) Regularly clean the compressor suction air filter and use an oil wetted suction filter.
6) Feed the minimum cylinder lubrication to compressor.
What are the safety devices on the start air line?
1) Safety valve.
2) Bursting disc.
3) Flame trap.
4) Starting air line drain valve.
5) Turning gear interlock.
6) Reversing interlock.
What are the 3 main safeties on air compressors?
1) Relief valves - After each stage of the compressor to release excess pressure when the pressure rises above the set value.
2) Bursting disc - Copper disc fitted in the water space of the coolers. If the tube fails, it will burst at a pre-determined pressure and release it.
3) Fusible plug - Fitted to the air receiver so in the event of a fire near the air receiver it will cause the core to melt and release the air.
What are the air compressor trips?
1) Lube oil low pressure.
2) Water temperature high.
3) Water no flow.
4) Motor overload.
What are the main defects with air receivers?
1) Defective safety valve.
2) High levels of condensate - corrosion and over cycling of compressor.
3) Blocked drain valve.
4) High oil content.
5) No clear indication of the safe working pressure on receiver.
What is a running direction interlock?
It is a blocking device that ensures the engine is only started or reversed when some conditions are satisfied.
Prevents the injection of fuel to the engine when the telegraph does not synchronise with the running direction of the engine.
What is a turning gear interlock?
Prevents the admission of starting air to the engine cylinders when the turning gear is engaged.
Necessary to prevent the turning gear and motor flying off and puncturing the bulkhead.
How do you check the efficiency on air compressors?
Time how long it takes for the receivers to fill.
What checks would you perform on the air compressor?
1) Pressure gauges for lube oil and water.
2) Abnormal sounds like knocking.
3) Lube oil or water leakages.
4) Check lubrication sight glass.
5) Check if discharge pressure is normal.
6) Check air temperature in final stage is under limit.
7) Check the flow of cooling water from sight glass.
8) Check free rotation of cooling water pump.
9) Check the relief valves for leakage.
10) Condensate drain function.
11) Compressor is in automatic.
What is the purpose of an intercooler on the air compressor?
To cool the air before the next stage of compression, as a higher density of cool air makes it easier to compress than hot air.
What maintenance would you carry out on an air compressor?
1) Lube oil change.
2) LP and HP valve overhaul.
3) Replacing lube oil filter.
4) Change air filter.
5) Clean coolers.
What interval checks are covered in the manual for an air compressor?
1) Bedplate bolts.
2) LP and HP valves.
3) Cylinder.
4) Pipe connections.
5) Big end bearings.
6) Piston and cylinder walls.
7) Flexible coupling.
8) Safety valves.
9) Main bearings.
10) Piston, gudgeon pin and rings and gudgeon pin bearings.
11) LO pump.
What is clearance in an air compressor?
The space between the piston crown and the cylinder head in order to stop the piston striking the compressor head.
What is an unloader in an air compressor?
An unloader uses solenoid or pneumatic control to release pressure during the starting of the compressor to reduce loading of the compressor due to high start up currents.
What is the purpose of a viscotherm?
To measure the viscosity of fuel oil at the fuel injection system.
What is viscosity a measure of?
The internal friction of a fluid, the thickness, its ability to pour.
What checks would you perform on a FO purifier?
1) Abnormal sounds or vibration.
2) Inlet and outlet fuel pressures.
3) Sludge discharge is not open in normal operation.
4) Proper ejection occurs.
5) Feed water correct pressure.
6) Leakage.
7) Sump oil level.
8) Motor overheating.
9) Product temperature.
10) Solenoid valve operation.
11) Break is disengaged.
12) Belt movement
How much capacity must a service tank have? What regulation details it.
Two fuel oil service tanks for each type of fuel used on board necessary for propulsion and vital systems or equivalent arrangements shall be provided on each new ship, with a capacity of at least 8 h at maximum continuous rating of the propulsion plant and normal operating load at sea of the generator plant.
SOLAS II-1/26.11
Due to the maximum UMS time being 8 hours.
What is the start-up procedure for a FWG?
1) Close the vent cock.
2) Open the ejector pump valve and sea water discharge valve.
3) Start the pump, slowly opening the ejector outlet.
4) Check the inlet pressure on the ejector is 4 bar or above.
5) Check the condenser air outlet valve is functioning correctly.
6) Open the feed water valve to 0.4-0.6 bar.
7) Start chemical injection if applicable.
8) Check vacuum is at 0.9 bar.
9) Slowly open hot water to fully open.
10) Close hot water bypass to adjust flow rate.
11) Switch on salinity indicator.
12) Check the distillate is visible through the sight glass.
12) Start the distillate pump, adjusting pressure to 1.4-2.2 bar.
13) Monitor the generating capacity with flowmeter over 30 minutes to ensure proper generating capacity.
What is the shutdown procedure for a FWG?
1) Open fully the hot water bypass.
2) Close fully the hot water outlet valve.
3) Close the hot water inlet valve.
4) Stop the distillate pump by closing the outlet valve.
5) Cool down the heater by running ejector pump for 30 minutes to supply feed water to the heater.
6) Stop chemical injection.
7) Switch off salinometer.
8) Stope ejector pump and open air vent.
9) Close the overboard valve.
10) Close the valve to the tank
