Q1. With reference to an engine air starting system
(a) Explain why a slow turning is fitted
(b) State, with reasons, when a slow turning system operates
(c) Describe, with the aid of a sketch, an air starting system, explaining how the slow turning system operates.
Q4. With reference to LNG diesel engine installations:
(a) Describe, with the aid of a sketch, a Gas Valve Unit, explaining its purpose and indicating where it is located in the gas train. (6)
(b) Explain why ventilation and inert gas systems must be installed with the engine fuel gas system. (5)
(c) State why pilot injection must be provided when burning fuel gas, explaining how a pilot injection system works (5)
Q3. State, with reasons, THREE properties required for a cylinder lubricant for a main engine operating on HFO.
(b) Describe, with the aid of a sketches, an electronically controlled cylinder lubrication system, stating how the timing and quantity of cylinder lubricant is regulated and set.
Q6. Selective catalytic Reactors (SCR) are being extensively used in marine diesel engines for the compliance of Tier-III NOx emission requirements. Explain various types of SCRs in use with particular focus on the following:-
a) High-Pressure SCRs (HPSCR) vs Low-Pressure SCRs (LPSCR)
b) SCRs with static mixers.
c) SCRs installed upstream the turbocharger(s) Vs downstream turbochargers.
Q5. (a) Explain the term torsional vibration, indicating the effect this can have on an engine crankshaft.
(b) Explain why a detuner/vibration damper might be fitted to an engine.
(c) Explain why an engine might have a barred speed range and why the engine should not be operated continuously in that range. (5)
Q6. (a) Describe, with the aid of sketches, the procedure for cutting out and "hanging-up" an engine cylinder of a two-stroke crosshead engine in the event of complete failure of the crosshead pin such that the crosshead pin cannot be operated and no replacement is immediately available. (12)
(b) State, with reasons, the factors which may inhibit starting and limit the operating speed of the engine with a cylinder cut out. (4)
Q7. With reference to a waste heat boiler/economiser:
a. Write a procedure for the cleaning the gas side of an exhaust gas boiler/economiser when the associated main engine is:
(i) running; (ii) stopped.
b. Write a procedure for operation of the main engine when the associated waste heat boiler/economiser cannot be operated due to tube failure.
Q8. a. Explain why top bracing is used for large crosshead engines. (4)
b. Describe, with the aid of a sketch, a hydraulic top bracing unit for a large crosshead engine indicating where the top bracing is fitted and how it operates. (6)
C. Write instructions for the checking of a large crosshead engine top bracing system and a holding down system. (6)
Q9. (a) Explain why variable exhaust valve closing can be advantageous in the operation of large slow speed main engines.
(b) Explain, with the aid of a sketch, how variable exhaust valve closing is achieved.
(c) Explain how high impact is avoided as the valve closes. (2)
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