Aux: Boiler

Manual Switch Operation Method

＜Select Switch Type＞
1. Turn the Manual-Auto Changeover Switch “Manual”.
2. Start to run FAN. At this time, carry out pre-purge sufficiently for 60 seconds or more.
3. Start to run Fuel Oil pump. The circulation starts. Check there are no leakage of the
combustion oil.
4. Turn ignition transformer (Pilot) ON.
In case of the pilot burner, check the combustion by the green lamp for combustion check.
At this time, be sure not to repeat ON-OFF operation again and again when the pilot burner
does not ignite. Be careful that the atomized fuels which could not be burnt are full in the
chamber, it is very dangerous.
5. Turn the solenoid valve ON.
Check the combustion by the green lamp for combustion check.
*With pilot burner : Turn both solenoid valve and ignition transformer OFF immediately if
the green lamp does not light up within 3 seconds after solenoid valve ON.
*Without pilot burner : Turn the both solenoid valve and pilot OFF immediately if the green
lamp goes off at proceeding from pilot to main.
6. Turn the ignition transformer (Pilot) which was turned to ON at the above procedure No.4
OFF.
*Procedure of 1～6 is the details for manual operation. If high combustion occurs, turn the
solenoid valve switch for high combustion ON in due order after No. 6 operation finishes.
*For C Heavy Oil, turn the heater switch ON. ON-OFF operation is started by the thermostat
or temperature controller operation. *If there are risks of FO dropping and atomizing in the
furnace by miss fire and so on, carry out purge sufficiently to decrease the temperature in
the furnace. Start manual operation after checking of no FO built up in the furnace. *Be sure
to check the notes about operation described also in the instruction manuals.

DANGER
NO BURNER TO BE IGNITED BEFORE THE FURNACE HAS BEEN PROPERLY
PURGED.

Start the boiler in automatic mode.

1. The burner fan will start the purging cycle which will remove any gases present in
the furnace by forcing it out through the funnel.
2. 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.
3. The main burner which is supplied by heavy oil catches fire with the help of pilot
burner.
4. Check the combustion chamber from the sight glass to ensure the burner has lit and
the flame is satisfactory.
How to build up the steam pressure and to put boiler into service
Cold starts place a much greater mechanical load on shell boilers than normal operation. A
cold start is unavoidable the first time the boiler is commissioned. However, procedures
similar to cold starts can also occur after initial start-up, e.g. after the boiler has been left
idle for some time.
The reason for the higher mechanical load during cold starts is the temperature difference
between the flame tube and the boiler shell, which is much higher than in normal operation.
For this reason, the flame tube expands more in relation to the boiler shell than in normal
operation. This creates, between the flame tube and the boiler shell or the flame tube and
colder flue pipes, a considerably increased mechanical load
1. Ensure that the vent valve on the boiler is open and check there is no pressure in the
boiler.
2. Check that the steam stop valve is closed.
3. 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
recommendation.
4. 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 feature which prevent
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.
5. Open the D.O valves and start the booster pump.
6. Start the boiler in automatic mode. Check the combustion chamber from the sight
glass to ensure the burner has lit and the flame is satisfactory.
7. Flash up the boiler at short intervals, for very small periods, to enable it to warm up
gradually. Failure to do so could lead to thermal stress. (follow the maker instruction
strictly.) When raising the pressure, keep the burner firing for 5 minutes and out of
service for 15 minutes repeatedly at the lowest fuel oil
8. Check any leakage during this process.
9. Close the vent valve after the steam starts coming outside.
10. Open the steam stop valve and put boiler into service.

State the function of safety valve and how to adjust the setting point to blow
Safety valves are fitted to protect the boiler from the effect of over pressure. At least two
safety valves are fitted to each boiler steam drum, but if there is a super heater, another
safety valve should be fitted on it.

Pressure Setting of the Boiler Safety Valve:

1. Safety valve pressure setting can be done from high to low pressure or vice versa.
2. Take necessary personal safety precaution and arrange tools i.e. gagging tool and
master gauges.
3. Slowly raise the boiler pressure and blow off the safety valves manually few times
for thermal expansion and to reduce the thermal stress on the valves.
4. Then screw down all the safety valves higher than the setting pressure at which you
are going to set.
5. Raise the boiler steam pressure 2-3 % more than the designed pressure of the boiler,
then stop firing and unscrew the first valve slowly, when it blows off at 2-3 % more
than the designed pressure then note this opening and closing pressure of the valve
and finally gag it.
6. Raise the boiler pressure at the designed pressure of the boiler and unscrew the 2nd
valve, when it blows off at designed pressure then note this opening pressure and
check the closing pressure also. Recheck the setting pressure and gag the valve.
7. Finally take out the gagging tools. Pressure setting should be done in presence of
surveyor
Operation methods of boiler and economizer under way
An economizer is installed in the stack of some boilers. The economizer saves energy by
using heat that would otherwise be lost to the atmosphere. The economizer is a heat exchanger
that pre-heats the boiler feed water with heat from the flue gases. Flue gases can
also be used to heat the combustion air being brought into the burner. The steam
generating plant consists of one auxiliary boilers and one exhaust gas economizer. Steam is
required at sea for fuel, domestic water and cargo slop tank heating purposes. The steam
demand of the plant, in port, is served by the boilers. At sea, steam demand is met by
circulating boiler water from the auxiliary boilers through the exhaust gas economizer, by
one of the boiler water circulating pumps. The auxiliary boiler acts as a receiver for the
steam generated by the economizer. The economizer is arranged in the main engine
exhaust gas uptake to take waste heat from the main engine exhaust. An auxiliary boiler
may be required at sea in low temperature areas, as well as reduced power operation of the
main engine, such as during manoeuvring or slow steaming on passage when there will be
insufficient waste heat to generate the required steam.

Precautions for using exhaust gas economizer

Flue Gas side care:
Flue gas side care and cleaning is one of the most important factors contributing to efficient
economizer operation and extended service life. It can also avoid economizer soot fire. An
effective soot blowing routine should be established and followed so solids will not
accumulate on the heat transfer surface, and every effort should be made to keep gas side
surfaces dry at all times.
Feed water side care and cleaning:
Feed water side care and cleaning is relatively simple since the procedures and materials are
identical to those used in boiler tube waterside care and may be done simultaneously on the
same schedule. Be aware that the feed water piping into the economizer may contain
impurities such as dirt and grease, particulates that must be eliminated before entering the
equipment.
What malfunctions/troubles likely happen to boiler on its operation
1. Failure in boiler starting - is a common phenomenon on ship. There can be several
reasons for the failure in staring of a boiler. In this article we will learn about the most
common reasons for not starting of boiler.
 Solenoid valve in the fuel supply line is malfunctioning
 Flame eye is malfunctioning:
 Pilot Burner nozzle is choked
 Electrodes are not generating spark
 Line filter at the inlet of the fuel line for burner is choked:
 Oil contamination of marine boilers
2. Boiler trip
3. Boiler back fire
How to keep boiler in cold condition while it is out of service
Stopping a boiler
1. If the boiler is needed to be stopped for longer duration for maintenance or opened
up for survey, change the fuel to distillate fuel.
2. If separate heating arrangement for heavy oil is present then there’s is no need to
change over to distillate fuel and the oil is kept on circulation mode.
3. Stop the boiler automatic cycle.
4. Close the steam stop valves.
5. Close the boiler feed water valves.
6. When the boiler pressure is just reduced to over atmospheric pressure the vent
valve is kept open to prevent vacuum formation inside the boiler.
The danger of oil entering a boiler with the feedwater
If oily matter get into boiler, it will adhere on the heating surface, causing overheat
regardless of the quantity. Furthermore, boiler water is easily saponified because it is
alkaline. Then it results in Carry-over caused by foaming of boiler water.
What is meant by “blow- back”
Boiler Furnace Blow Back
Boiler furnace blow back is an explosion caused by accumulated fuel vapor inside
furnace catches fire and develops high pressure inside the furnace. It is also called boiler
furnace back-fire.

How blow-back can be avoided

Blow-back can be avoided by preventing following condition from happening?
1. Unburnt fuel leftover in the furnace during previous
operation.
2. Fuel leak to the furnace before ignition. 3. Presence of flue gases in furnace.
4. Pre-purge and post-purge timings are not enough.
5. Incorrect burner settings.
6. Improper ratio of fuel and air volume.
7. Burner malfunctioning /Controller malfunctioning.
8. Outlet damper opening less.
9. Repeated unsuccessful start attempts for boiler firing.