Incinerator is an important machinery on board which reduces the cost of waste disposal for ships. It is used to burn solid and liquid wastes produced on ships during normal operations and is also important for reducing overall waste from ships.
Considered to be an important MARPOL equipment, incinerator needs proper knowledge and guidelines for maintenance and operations.
Wrong operation or under maintenance of incinerator may reduce the overall efficiency of the equipment and can also lead to serious accidents.
Marine Insight reports of the eight common problems that occur in ship’s incinerator and how to deal with them.
Flame Failure Alarm
One of the first things that needs to be done when receiving flame failure alarm is to check the flame sensor. More than often flame sensors get dirty resulting in flame failure alarm. In such cases take out and clean the sensor before fitting it back. That would solve the problem (If the sensor is defective, put a new one).
Some other reasons for flame failure alarm are:
- Dirty Burner
- Ignition failure
- Blocked diesel oil nozzle
- Defective flame sensor
- Defective solenoid valve
- Incorrect opening of air damper
- Clogged fuel line filter
In case of dirty burner, engineers will have to clean the burner’s flame scrod and blast tube. If that doesn’t solve the issue, check the spark electrodes, which can be the reason for ignition failure. Problem of ignition failure related to spark electrode can be solved by cleaning and adjusting them.
In case of blocked diesel oil nozzles, replace them with clean ones. A defective solenoid valve can also lead to flame failure alarm. If the same is found, replace the solenoid valve/coil.
Lastly, incorrect opening of air damper might be preventing the right amount of air from reaching the combustion chamber, resulting in ignition failure. Check the opening and closing of air damper to solve the issue.
High Flue Gas Temperature Alarm
There can be several reasons for high flue gas temperature alarms and the most common one is faulty or defective temperature sensor.
Some of the other reasons for this alarm are:
- Blocked air cooling inlet
- Faulty inverter and transmitter
- Leaking or defective solenoid valve
- Leaking dosing pump stator
- Defective pressure control
- Clogged cooling panel slot
- Throttling brick fallen out
Faulty inverter and transmitter circuit and input should always be checked and inputs adjusted as required. Pressure control and solenoid valves should be checked at regular intervals of time.
High Combustion Chamber Temperature Alarm
Main reasons for high combustion chamber temperature alarm are:
- Faulty alarm sensor
- Solid waste inside the incinerator is more in quantity
- Poor refractory condition
High combustion chamber temperature alarm can also occur if the outlet is blocked with slag or the slot at the combustion chamber floor level is blocked.
Sludge Oil Leaking
Sludge oil leaking mainly takes place from the base plate corners of the combustion chamber. Some of the main reasons for sludge oil leaking are:
- Improper opening of oil burner air damper
- Very low under-pressure
- Closed Atomizing valve
- Incorrect valves in Programmable logic controller (PLC)
- Blocked sludge nozzle atomizing slot
Make sure the atomizing slot is open 3/4th to 1 full turn and the valves in the PLC are set as per those mentioned in the manual. Check the under-pressure control function incase the under pressure is too low.
If the air damper is not working properly, check it’s opening and closing functions. Also make sure to open and clean the sludge nozzle atomizing slot if it’s blocked.
Cracks in Refractory of Combustion Chamber
The main reason for cracks in combustion chamber refractory is rapid change in temperature caused by filling of water in the sludge tank during sludge operation at high temperature. It should always be noted not to fill the sludge tank when the sludge is burning.
Vibrations of the machinery are also a prime reason for this problem. Adequate deck support should be reinforced to prevent this.
Leaking door gaskets can also lead to this issue. Adjust and change the gaskets whenever required.
Draft failure / Low Pressure Alarm
One of the main things to check for solving problems related to draft failure or extremely low under pressure alarm is faulty pressure sensor. Some other reasons for the problem are:
- Damaged door gasket
- Broken fan belt
- Wrong rotation of fan direction
- Failure in opening of flue gas damper
- Leakage in sensor tube
Always make sure that fan belt and door gasket are properly checked at regular intervals of time. Faulty fan, flue gas damper and sensor tube must also be checked and repaired as required.
Leaking Mechanical Seal Sludge pump
In order to prevent leaking of mechanical seal, it should be noted that the sludge pump is not running dry for a long time. If need arise, change the seal. Also, large amount of debris in the sludge can also damage the mechanical seal. In such cases, restart the system by flushing and cleaning the lines.
Leakage in D.O. Pump Shaft End
The main reason for this problem is blocked return. Open the return valve or remove return blocking. Replace the shaft seal if required.
These are some of the main issues that occur with the ship’s incinerator. Regular maintenance and checks are extremely important to ensure smooth and safe operations of this important ship machinery system.
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Source: Marine Insight
