The boiler is provided with heavy or marine gas fuel oil for generating the heat in the furnace. To ensure the fuel system is operating efficiently, it is fitted with the following boiler safety features:
Low fuel oil pressure alarm:
The fuel to the burner is provided using a fuel oil pump. Two pumps are installed (one kept on standby) to ensure there is no operational hindrance in case of failure of one pump. If the fuel supply pressure is less than required, the atomization of fuel will not happen, leading to the dripping of fuel inside the furnace.
This can lead to blowback of the burner and can seriously injure the operator. Once the low-pressure alarm is sounded, the operator must ensure to eliminate the cause behind it.
Low/high fuel oil temperature alarm:
Modern marine boilers are meant to operate in different grades of fuel due to the port / ECA regulations for minimizing the air pollution from the ship. The oil temperature is an important factor as it controls the viscosity of the fuel which is directly related to atomization and efficient combustion inside the furnace.
If the fuel temperature is not at its set value (which will vary for different grades), the alarm will sound. The operator must stop the alarm and the oil temperature should be brought to normal before restarting the boiler.
Flame failure alarm:
The burner unit which is a photocell (also known as the flame eye) is used to detect the flame inside the furnace. If the burner is abruptly stopped, or during starting the main burner is not producing flame, the photocell will detect the absence of the flame and sound an audio-visual alarm.
Smoke Density alarm:
With more stringent rules coming up for environmental protection, the boiler exhaust is fitted with a smoke density sensor that detects the post-combustion product, especially during starting of a boiler and at low loads. If the smoke density is higher than the required value, it will sound an alarm which the operator needs to check the combustion of the boiler.
Force draught fan stop alarm:
To have efficient combustion, a proper mixture of air and fuel is needed. The air is provided to the burner assembly using a forced draught fan (FDF). If the fan is not operational due to any reason, it will generate an alarm.