Economisers

Question 1

1. With reference to exhaust gas economisers:
   a) State why regular soot blowing is considered necessary; (4)
   b) Explain why it is important to maintain the exhaust gas temperature above the dewpoint; (6) c) List three indications of an exhaust gas economiser fire; (6)

Answer 1

a) To prevent an excessive accumulation of carbon deposits within the economiser. To reduce the risk of economiser damage from fire and overheating.
b) To prevent damage from acidic corrosion within the exhaust space.
To prevent cold corrosion attacking exhaust components and cylinders due to wash down. c) Increased economiser pressure.
Paint discolouration of economiser.
Falling embers and smoke from economiser.
Safety valves lifting.

Question 2

2. With reference to fires in diesel engine uptake economisers:
   a) State TWO indications of a fire in an economiser; (4)
   b) List the course of action to be taken in the event of discovering a fire whilst on passage. (12)

Answer 2

a) Violent stream of sparks and flames from the uptake.
High economiser pressure
b) Raise the Fire Alarm.
Inform the Bridge of the situation and request that the engine is slowed.
Start additional circulation pump.
Call C/E and emergency engineers.
Start the emergency generator and fire pump.
Stop all mechanical ventilators within the machine space
Close all fire dampers
Assemble boundary cooling of the engine casing, using flood quantities of water attack the fire.
Cover T/C with sheeting to prevent air getting to fire.
C/E order drenching system, if fitted.