EKG-July-21-(2)

Q1. A. Describe an automatic self de-sludging centrifuge suitable for dealing with the fuel of density up to 1010 kg/m3 at 150℃;

B. Explain how the centrifuge described in Q1 (a) is able to remove water from a fuel that has a density that is higher than that of water and state factors that may assist the operation.
C. As Second Engineer, write down the start-up procedure for the centrifuge described in Q1 (a) for the benefit of your staff;
D. State how the problem of catalytic fines in fuel oil may be dealt with.

Q2. With reference to the carriage and pumping of liquefied gas cargo: 

A. Sketch a suitable pumping system labelling the component parts; 

B. State; 

i) Why submerged hydraulically driven pumps are not used; 

ii) How overheating of pump drive shaft bearings is avoided; 

C. State, how the risk of fire and explosion in cargo tanks is obviated both in the loaded and discharged condition.

Q3. With reference to electro-hydraulic steering gears: 

A. Explain in terms of control parlance, the function of the “Hunting gear”; 

B. Explain the consequences if the standby pumping unit is motored; 

C. State TWO methods employed to prevent the standby hydraulic pump from being motored by the operating unit.

Q4. A. Explain the necessity of intercoolers on a multi-stage compressor. What attention is required to keep them safe and in good working order? Sketch and describe an intercooler suitable for a 2400kpa compressor and state materials used. 

B. What attention is needed before opening up for inspection? 

C. What faults are likely to develop in an air compressor and how are they remedied.

Q5. With reference to multi-tubular heat exchangers explain: 

(A) How and where impingement attack is likely to occur in the tubes 

(B) Why is it desirable that the coolant flow rate should not exceed that required to maintain the correct fluid temperature 

(C) Ample well-shaped water boxes and smooth tube inlets are desirable 

(D) Partial obstruction of tube bore is a common cause of tube failure?

Q6. With respect to refrigeration gases used on-board vessels, answer the following: 

A. Explain the Ozone Depleting Potential of conventional refrigerant gases. 

B. Name the alternate refrigerant gases available and being used onboard. 

C. What are the steps are taken to minimize the release of refrigerant gases from the plant during normal operation and maintenance activities?

Q7. A. Describe the procedure to be adopted for the inspection of a safety valve fitted to an exhaust gas boiler stating, with reasons, which parts should receive particularly close attention. 

B. Describe the procedure for the setting of safety valves of exhaust gas-fired auxiliary boilers; 
C. Explain the action taken after the setting of safety valves as in (B).

Q8. Cast iron is the most widely used metal after steel in Marine Engineering. Most cast irons consist of graphite in steel like matrix. Discuss the variation of properties that may arise with reference to pearlitic grey cast iron and spherical grey cast iron. Describe briefly the treatment necessary to produce these

two types of Irons.

Q9. With respect to Energy-efficient running of ships; 

(a) Sketch and explain the optimization of propeller hull interface flow devices and improvement of propulsion efficiency. 

(b) sketch and explain the optimization of Auxiliary machinery using VFDs.