Thursday, February 24, 2011

MAIN ENGINE SCAVENGE FIRE , ON CHEMICAL TANKERS-- CAPT AJIT VADAKAYIL




SCAVENGE FIRE CHECK LIST


Cb
S No

                                                 Description


INDICATIONS

1
Activation of High temperature alarm of the respective unit’s scavenge port .

2
High Exhaust temperature.

3
Abnormal behavior of Main Engine.

4
Surging of Turbochargers with smoke emanating.

5
Sparks / flame from scavenge drain ( check under piston space through sight glass if fitted )

6
Heavy black smoke from funnel, sparks are visible at night.

7
Hunting due to unbalance of power on each cylinder.



ACTION


Inform bridge and Chief Engineer. Activate Engineer’s call alarm.


Increase Cylinder Lubrication to maximum


Change over ME controls from bridge to ECR.


Instruct crew to keep clear of scavenge doors


Slow down Main Engine to dead slow ahead—if not automatically slowed down.


Stop the auxiliary blowers and decrease fuel handle for 0.5 bars scavenge pressure.


Shut the scavenge drains of affected unit—ensure they are shut all the time.


Use relative wind to keep soot on poop deck.


Cut out unit and change over  to D.O.


Start Standby Auxiliary Engine.


Stop the Fresh Water Generator.


Stop Main Engine. Do not stop any circulating (J. C .W., P. C. W., L. O.) pumps.


Engage turning gear immediately, open indicator cocks and keep turning engine , all the while operating Cylinder lubricator manually.


Cover Turbo Charger air suction filter and shut off Engine Room fans to reduce ingress of air.


Drain off water from steam smothering line.


Inject dry steam to the unit concerned and wait for temperature to fall.


Keep portable extinguishers standby near scavenge doors.


After the fire is extinguished, first wait for the temperatures to fall and then only open scavenge doors .


Clean scavenge space and check carefully for any damage. Examine the condition of scavenge valves, piston rings, stuffing box, liner & piston rod.


Clear scavenge drains and clean the scavenge space.


With main LO pump running check the scavenge spaces for LO leakage.


Start Main Engine and operate under strict monitoring.


Revert back to original MECYL feed rate .


Find out the cause of the scavenge fire and take action to prevent recurrance.



PROBABLE CAUSES

a
Gas blow by due to liner wear.

b
Gas blow by due to bad piston rings.

c
Excessive accumulation of sludge in scavenge spaces.

d
Poor atomization / combustion due to bad injection nozzles.

e
Prolonged slow speed operation of M/E with poor quality combustion.

f
Leakage of piston cooling lubricating oil.

g
Excessive MECYL lubrication.

h
Hot spots due to insufficient MECYL feed.


Notes:
Thermocheck by touch and feel to see if scavenge drain pipes are clogged. If so remove sludge.

Read fuel analysis reports and take corrective action for proper viscosity injection

Keep a watch on reconditioned and suspect piston crowns.

Visually inspect from scavenge ports to check leakage of MECYL.

Most efficient way is to inject steam as soon as engine is stopped with propeller still turning engine on inertia.

Fire in scavenge AIR space can trigger explosion in exh gas manifold and damage constant pressure T/C. The BDC cylinder will have both ports open –flame will burn liner. Hence you must consider to cut off fuel to cylinder which is on  fire.


CAPT AJIT VADAKAYIL
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1 comment:

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