Answer EKM Question 27
Q27. State the probable engine defects and rectifying action needed if the following conditions are indicated on a single unit of a large two-stroke marine diesel engine having seven units. State any additional information which might be of help in forming on opinion
1. Increased exhaust temperatures.
2. Reduced exhaust temperature.
3. Reduction in jacket cooling water return temperature.
4. Increase in jacket cooling water return temperature.
Answer: 1. Increased Exhaust temperatures:
A. Probable Engine Defects:
a. A faulty fuel injector causes an improper atomization. This may be because of seized Needle valve, broken or weaker spring. This will cause excessive fuel injection combined with altered timing causes the fuel to burn after the power stroke and the fuel burning in the exhaust manifold.
b. Inadequate supply of inlet air due to scavenge related issues causes improper combustion hence fuel burning in the exhaust manifold. May cause scvange space fire in the affected unit.
c. Faulty temperature sensors:
d. Leaky exhaust valve.
e. Fuel rack is stuck fully open.
B. Rectifying Action:
a. Ensure the deviation is factual and not false alarm by checking the local thermometer.
b. Ensure the fuel rack is free and not stuck.
c. Check and ensure the exhaust valve functioning, its timing to be checked for correctness.
d. Ensure the scvange pressure is normal and the air suppy is normal.
e. Take indicator card and analyse the cause if there are any issuses like late injection, leaky exhaust valve etc.
C. Additional Information: Regular inspection of fuel rack position, engine load, jacket cooling temperaure and other parameters.
2. Reduced exhaust temperature:
A. Probable Engine Defects:
a. A faulty fuel injector causes an improper atomization. This may be because of seized Needle valve, broken or weaker spring. This will cause less fuel injection and cause low power development.
b. Inadequated supply of inlet air due to scavenge related issues causes improper combution hence fuel burning in the exhaust manifold. May cause scvange space fire in the affected unit.
c. Faulty temperature sensors:
d. Leaky exhaust valve.
e. Fuel rack is stuck fully open.
B. Rectifying Action:
a. Ensure the deviation is factual and not false alarm by checking the local thermometer.
b. Ensure the fuel rack is free and not stuck.
c. Check and ensure the exhaust valve functioning, its timing to be checked for correctness.
d. Ensure the scvange pressure is normal and the air suppy is normal.
e. Take indicator card and analyse the cause if there are any issuses like late injection, leaky exhaust valve etc.
C. Additional Information: Regular inspection of fuel rack position, engine load, jacket cooling temperaure and other parameters.
3. Reduction in jacket cooling water return temperature:
A. Probable Engine Defects:
a. Faulty temperature sensor.
b. Fuel oil cut out or low fuel injection, it may be because of defective injector or pump.
c. Improper heat transfer, it may be because of scale formation in jacket or air trapped in the jacket cooling water system.
B. Rectifying Action:
a. Ensure the engine is balanced, i.e power output from every unit is equal.
b. Ensure the deviation is factual and not false alarm by checking the local thermometer.
c. Purge any air in the system and keep the cooling water treated chemically.
C. Additional Information: Keep watch for any leakage of cooling water and bypass valve poition to keep the temperature within limit.
4. Increase in jacket cooling water return temperature:
A. Probable Engine Defects:
a. Faulty temperature sensor.
b. Fuel oil injection is excessive or overloaded engine.
c. Improper cooling water supply.
d. Scvange fire or crack in cylinder liner.
B. Rectifying Action:
a. Keep the temperature sensors maintained.
b. Check if the engine units are equally loaded.
c. Check the cooling water supply is adequate.
d. Maintain the engine as per the maker recommendations to prevent any unfortunate scvange fire or cylinder crack.
C. Additional Information: Keep watch for any leakage of cooling water and bypass valve position to keep the temperature within limit.
1. Increased exhaust temperatures.
2. Reduced exhaust temperature.
3. Reduction in jacket cooling water return temperature.
4. Increase in jacket cooling water return temperature.
Answer: 1. Increased Exhaust temperatures:
A. Probable Engine Defects:
a. A faulty fuel injector causes an improper atomization. This may be because of seized Needle valve, broken or weaker spring. This will cause excessive fuel injection combined with altered timing causes the fuel to burn after the power stroke and the fuel burning in the exhaust manifold.
b. Inadequate supply of inlet air due to scavenge related issues causes improper combustion hence fuel burning in the exhaust manifold. May cause scvange space fire in the affected unit.
c. Faulty temperature sensors:
d. Leaky exhaust valve.
e. Fuel rack is stuck fully open.
B. Rectifying Action:
a. Ensure the deviation is factual and not false alarm by checking the local thermometer.
b. Ensure the fuel rack is free and not stuck.
c. Check and ensure the exhaust valve functioning, its timing to be checked for correctness.
d. Ensure the scvange pressure is normal and the air suppy is normal.
e. Take indicator card and analyse the cause if there are any issuses like late injection, leaky exhaust valve etc.
C. Additional Information: Regular inspection of fuel rack position, engine load, jacket cooling temperaure and other parameters.
2. Reduced exhaust temperature:
A. Probable Engine Defects:
a. A faulty fuel injector causes an improper atomization. This may be because of seized Needle valve, broken or weaker spring. This will cause less fuel injection and cause low power development.
b. Inadequated supply of inlet air due to scavenge related issues causes improper combution hence fuel burning in the exhaust manifold. May cause scvange space fire in the affected unit.
c. Faulty temperature sensors:
d. Leaky exhaust valve.
e. Fuel rack is stuck fully open.
B. Rectifying Action:
a. Ensure the deviation is factual and not false alarm by checking the local thermometer.
b. Ensure the fuel rack is free and not stuck.
c. Check and ensure the exhaust valve functioning, its timing to be checked for correctness.
d. Ensure the scvange pressure is normal and the air suppy is normal.
e. Take indicator card and analyse the cause if there are any issuses like late injection, leaky exhaust valve etc.
C. Additional Information: Regular inspection of fuel rack position, engine load, jacket cooling temperaure and other parameters.
3. Reduction in jacket cooling water return temperature:
A. Probable Engine Defects:
a. Faulty temperature sensor.
b. Fuel oil cut out or low fuel injection, it may be because of defective injector or pump.
c. Improper heat transfer, it may be because of scale formation in jacket or air trapped in the jacket cooling water system.
B. Rectifying Action:
a. Ensure the engine is balanced, i.e power output from every unit is equal.
b. Ensure the deviation is factual and not false alarm by checking the local thermometer.
c. Purge any air in the system and keep the cooling water treated chemically.
C. Additional Information: Keep watch for any leakage of cooling water and bypass valve poition to keep the temperature within limit.
4. Increase in jacket cooling water return temperature:
A. Probable Engine Defects:
a. Faulty temperature sensor.
b. Fuel oil injection is excessive or overloaded engine.
c. Improper cooling water supply.
d. Scvange fire or crack in cylinder liner.
B. Rectifying Action:
a. Keep the temperature sensors maintained.
b. Check if the engine units are equally loaded.
c. Check the cooling water supply is adequate.
d. Maintain the engine as per the maker recommendations to prevent any unfortunate scvange fire or cylinder crack.
C. Additional Information: Keep watch for any leakage of cooling water and bypass valve position to keep the temperature within limit.
Comments
Post a Comment