Answer EKM Question 32

Q32. During recent months a number of fuel injector needle valves have seized in their bodies during engine operation. 

a. Explain the effects on engine operation. 

b. State the possible causes. 

c. As Second Engineer, state with reasons, the instructions to be issued in order to minimize this problem.

Answer: A Needle valves can be seized. 

In partially open condition 

In fully closed position or 

In fully open condition. 

1. Seized in partially open condition CalICPC lace artictrnt of fuel injection — Vow power. Improper atomization causing black smoke. high exhaust gas temperature. Dribbling - After burning, black smoke 2..90M In my Closed position _ . . + causing nil fuel infection, no flower production other units will overload, Low exhaust temperature, Engine unbalanced. 3"-Ilethgtinfultisiltenteeditinn. + Causing the Injector to inject earlier and the injector to dribble - Improper atomization, High exhaust gas temperature and black smok5Loss of power 

B. State the possible causes. 

Overheating of the fuel injector nozzle due to inadequate cooling, clogged nozzle cooling water passage, oil contaminated water etc. >> Abrasives in the fuel from inadequate fuel preparation due to improper purification, inferior quality of fuel 

Low sulphur operation - Low sulphur ineinTroilubricity and hence the pump plunger and the needle valve will seize 

Overloading of engine= Engine overloading elsO can cause the nozzles to seize. L, 

C. As Second Engineer, state with reasons, the instructions to be issued in order to minimize this problem.

The following actions to be taken to minimize the seizing of fuel injector needle valve: 

fuel purification: Ensure/fuel-Oil separators are maintained regularly and operates with optimum throughput, too high throughput will also cause improper separation. 

Ensure Fllets are running continuously and the service tank overflows to settling tank, if the ship is equipped with old type purifier, ensure the purifiers operate in purifier and clarifier mode. 

All watchkeepers to drain the settling and service tank at frequent intervals for water and also for settled sludge. 

'• Euelsilxarameters .- 

Injection perimeters of the fuel oil to be maintained at recommended values, correct injection temperature and viscosity to be maintained at all time. Fuel oil additives . 

Especially in Low sulphur operation, to Improve the lubricity of the fuel additives are preferred. if such method is adopted, regularly check and dose the additives. J■ionle roofing system 

Usually nozzle cooling water system gets contaminated too frequently due to nozzles leaking fuel, if any such leak is identified, immediately rectify the leak and clean the system and replenish the system with fresh load of water 

Conduct cooling water test on the water to ensure, NCW quality is maintained well fuel filters

Ensure the fuel filters on the inlet of the engine and automatic filters in the system are functioning normally and regularly cleaned and the back washing is working in good condition. 

Maintenance  

Fuel injectors to be maintained as per manufacturer recommendation and the nozzle has to be renewed at correct interval. Reconditioning of the needle valve onboard is not possible. 

Storage 

Fuel injector nozzles should be stored in an air tight container to avoid any dust particle entering into the needle passage, properly coated with lubricating oil to avoid corrosion. To be stored in recommended temperature throughout its shelf life.