[icedcappucino]

PRECAUTIONS PRIOR TO LIGHTING BOILERS
The Engineer Officer in charge of this process must ensure that procedural checks are carried out. These include but not limited to:
• That all system valves and boiler mountings are operational and correctly set.
• That the boiler is filled to the requisite level to allow for expansion with correctly dosed water and no leakage is evident.
• Having established furnace spaces as uncontaminated, that the burner casing and gas register doors have been correctly fitted.
• That oil burners and associated system equipment and valves are correctly assembled and set in accordance with the manufacturer’s instructions.
• That furnaces have been sufficiently purged (a minimum of five full changes of furnace air).

RAISING STEAM/ cold start.
Precautions on Starting Boiler
Before start-up of the boiler plant, following general work and check procedures must be considered.
• Check that the main steam valve, by-pass valve and circulation valves, scum valve, and blow-down valves are closed.
• Open the feed water valves and the air vent valve. Fill the boiler with feed water to approximately 50-70 mm below normal water level.
• When filling a pressure less boiler, the feed water pump discharge valve must be throttled. Otherwise the pump motor will be overloaded.
• Check that the water level control system is connected and operational.
• Check the oil system and start the fuel oil supply pump. Pre-heat the fuel oil if the burner should operate on heavy fuel oil.
• Check the burner and the safety functions are working according to the manufacturer instruction.
• ENSURE BOILER PRESSURE GAUGE IS WELL CALIBRATED and sensing line valves for all the gauges and alarm sensors, level indicators are open.

Purging:
Boiler furnace is to be thoroughly purged prior putting burner on auto ignition mode during cold start. Should the burner fail to ignite or flame failure occurs, then it is essential that the furnace is visually examined for unburned fuel and purged before any attempt is made to re-ignite the burner.

Boiler Flashing:
When the boiler is started, the flashing up rate of the boiler must not be accelerated too much as this leads to an unnecessary over strain of the boiler material by quick and uneven temperature rises leading to premature failure of the tube/furnace refractory/water wall. It is necessary to perform a number of start/stop sequences to have even heating rate & gradual pressure build up. Burner must therefore only be operated at minimum load and in intervals of 1-2 minutes for the first two hours. Between each operation interval the burner should remain stopped for approximately 10-12 minutes. A period of six hours should normally be allowed for raising steam, but in cases where repairs to refractory, or repairs of parts subject to pressure have been carried out this period should be extended to 24 hours. Check the water level in the water level gauges frequently during the complete start-up. The water level gauges should be blown down several times to ensure a correct indication.
In cases of emergency when steam is required at short notice the boiler manufacturer’s instructions are to be adhered to

Venting:
Throughout the steam raising process, provision is to be made for venting all air from the boiler. This should be done solely by means of a designated air release cock. Under NO circumstances are the steam connections of the water level gauge glasses to be used for venting purposes. Once dry steam is vented out from the steam vent valve, approx. at pressure of 1.5 bars, the vent valve is closed.

MANUAL FIRING:
The boiler is now ready for firing for extended period, however build pressure slowly in 2 hrs time to normal working pressure. Pressure rise should be done in steps of 2 bars. During this time check and adjust tightness of the manhole covers, inspection covers, hand hole covers, flange bolts of boiler mountings.

AUTO FIRING:
Burner can be switched to auto firing mode once the steam pressure has reached 1 bars below the normal working pressure.

[Author]

Posts