Emergency Shut Down.
Power failure – I D fan , F D fan/s, Stoker/s and Feed-pumps motors stopped.
If this occurs shut-down the boiler as follows:
Note If the steam demand is high the water level in the boiler will fall quickly.
While water is visible in the gauge glass there is no danger of damage to the boiler.
1 Close the main steam stop valve.
Note : Because the ignition arch and guillotine door refractory are red hot when
power failure occurs, the coal will continue to ignite and then burn back
into the stoker hopper. To prevent this proceed as follows.
2 Rotate the grate by hand as follows,
Remove the grate indicator disc and cover.
Remove the shear pin.
Connect the crank handle to the squared end of the worm shaft and rotate
the grate by hand until the ignition line is visible under the ignition arch
( this can be seen through the spy hole in the ignition arch ).
Although the fire on the grate will loose most of its heat when power
failure occurred and the fans stopped it will be kept alive by natural
draught if the I D damper is open.
Set the F D single knob control unit to manual and its lever to the fully
closed position.
Set the I D damper control unit to manual and its control lever to 2 or 3 to
Maintain a slight draught above the fuel bed. The draught gauge should
read approximately minus 3 pa.
If the power is restored within 30 minutes , reset the boiler controls and
restart the boiler.
If the power is not restored within 30 minutes, bank the fires.
Do not forget to remove the ash from the boiler furnace.
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ReplyDeleteA process industry maintains a pilot tank, of capacity 1000 gallon, of group 3 (gasoline) fuels for firing its boiler’s burner in case emergency boiler shut down occurs. 500 gallons of fuel is required to start the boiler every time an emergency shutdown occurs. The temperature of fuel at the time of unloading in the tank was 113 °F. On one cold winter night, emergency shutdown occurred two times in quick succession. The operator on checking the fuel level found that amount of fuel left after the first shutdown was less than 500 gallons. Without analysis of the situation properly he put up a request for extra fuel from the stock tank. What was the amount that the operator requested? Assume tank temperature on that night was 59°F.