A boiler is one of the machinery that gets the ship going. A boiler is something, though not required continuously in operating a ship, cannot be done away with.
It is noted that the following steps may not apply to all types of boilers and each boiler requires some additional steps to be followed as per its system design. However, the basic steps remain the same.
Starting a Boiler
- Ensure that the vent valve on the boiler is open and check there is no pressure in the boiler.
- Check that the steam stop valve is closed.
- Check that all the valves for fuel are open, and let the fuel circulate through the system until it comes to the temperature required by the manufacturer’s recommendation.
- Check and open the feed water valves to the boiler and fill the water inside the boiler drum to just above the low water level. This is done because it is not possible to start the boiler below the low water level due to safety features that prevent the boiler from starting. Also, the level is not filled much because if filled too much, the water inside the boiler might expand and over-pressurize the boiler.
- Start the boiler in automatic mode. The burner fan will start the purging cycle which will remove any gases present in the furnace by forcing them out through the funnel.
- After the pre-set purge time the pilot burner will ignite. The pilot burner consists of two electrodes, through which a large current is passed, via the transformer, producing the spark between the electrodes. The pilot burner is supplied with diesel oil and when the oil passes over, the former ignites.
- The main burner which is supplied with heavy oil catches ignition with the help of the pilot burner.
- Check the combustion chamber from the sight glass to ensure the burner has lit and the flame is satisfactory.
- Keep a close eye on the water level as the pressure increases and open the feed water when the level of water inside the gauge glass is stable.
- Close the vent valve after the steam starts coming outside.
- Open the steam stop valve.
- Once the working steam pressure is reached, blow down the gauge glass and float chambers to check for the alarms.
Stopping a Boiler
- If the boiler is needed to be stopped for a longer duration for maintenance or opened up for the survey, change the fuel to distillate fuel.
- If a separate heating arrangement for heavy oil is present then there is no need to change over to distillate fuel and the oil is kept in circulation mode.
- Stop the boiler automatic cycle.
- Close the steam stop valves.
- Close the boiler feedwater valves.
- When the boiler pressure is just reduced to over atmospheric pressure the vent valve is kept open to prevent vacuum formation inside the boiler.