Correct procedure for water filling in boiler steam drum :-
Today we discussed about the correct method of boiler steam drum water filling. How to take water in boiler steam drum in safe manner. What are the talks remember during the boiler water filling . in power plant sector steam is generated with the help of water heating inside the boiler furnace and the water Is get heated and converted into steam and this steam is used by industrial purpose in process or electricity generation , so the boiler is initially filled with the D.M water . Economizer, water wall panel and evaporator are to be filled before boiler light up started. We all known about very well that water is pumped into the boiler steam drum with the help of B.F.P (Boiler Feed Pump) . This pump take the water from the Deaerator and reaches the water into drum through economizer, water wall and evaporator . From drums, water comes down through down comer tubes and evaporators water wall are gradually filled up. When all the tubes are filled up then the water level in the drum get started increases. if any air he present into the economizer or evaporator water wall is vented out during initial filling of boiler. If air is not vented out then it effects the heat transfer. For air vented out through boiler easily air vent is provided at economizer and steam drum. If we know about the water holding capacity of any boiler we can say that “the total water that is hold at different heat transfer element of the boiler & how much feed water is required for initial filling up of boiler “. Different -2 boiler manufacturer design the different-2 boiler have difrent-2 water holding capacity.
Drum water filling is a very important activity before boiler light up . in boiler hydrostatic test we also filling the drum with above method but in this condition little bit variation in the process of water filling . first of all insure that the suitable D.M water level is available in deaerator after that check out healthyness of the boiler feed pump . before start up of the boiler feed pump insure that the delivery valve should be closed condition after that slowly slowly open the discharge valve regulate the feed water supply with the help of control valve . water started filling into the boiler drum through economizer , water heater and evaporator after that drum level goes increases slowly -2 then water goes for the bottom ring header to water wall panel ,after water valve filling drum level goes increase up to the 100 % level after some time boiler pressure slightly increase when the drum pressure raise 1.5- 2.0 kg/cm2 water coming out from the boiler steam drum , immediately closed the air vent of the steam drum . then water goes for the super heater area after filling the super heater insure that the startup vent should be closed and MSSV ( main steam stop valve ) also in closed condition . Drum pressure gradually increases slowly -2 when then pressure reaches according to the permissible condition check out the or we can say inspection work inside the boiler carried out for checking any tube leakage or moisture found.
And also check out before hydro test boiler gauge glass should be isolated or drum safety valve and line safety valve should be gauged.
Following steaps to be taken consideration before starting water filling in boiler steam drum:-
-Water treatment report for the quantity of water being filled up should be available and confirm to the specifications.
-Steam drum water gauge glass should be taken into line for showing the correct level of steam drum for showing correct reading of pressure.
-Gate wall never ever be throttled it should be kept fully open or closed .
-All the Pressure gauges of Economizer headers, Steam drum & main steam line should be taken into inline.
-Main steam stop valve of boiler should be in closed position.
Procedure of water filling in boiler steam drum :-
-Make up Deaerator storage tank level with sufficient D.M water. When boiler is in shut down condition normal temperature water may be used.
-Start the DM water pump as per the start up procedure. Open the filling line isolation valve Gradually and fill up the boiler.
-Insure that the cooling water is available for the boiler fee pump for its gland cooling. Also check healthiness of pump .
-Start the boiler feed pump keeping the discharge valve in closed position.
-Check the boiler feed pump any vibration, abnormal sound, temperature and also how much current taken in no load or on load condition.
-Then open discharge valve slowly -2 of boiler feed pump and also check the any changes take place into vibration , sound , current taken, suction pressure etc.
-Check out boiler economizer air vent and steam drum vent are in open condition.
-Start taking feed water in to economizer slowly by opening the feed water discharge control valve. if feed water is hot, it should enter in to economizer slowly to avoid thermal shock.
-After some time feed water started comes out through economizer vent.
-When the water comes out from the economizer vent then close the economizer vent isolation valve. Flow of feed water controlled by the feed water control valve.
Now water will started entering in the steam drum. From steam drum this water will come down through the down comer and water wall tubes evaporators will be filled up gradually.
When all the tube filled up after that drum level will starting rising.
Keep the drum level in normal working level. When the boiler light up started, temperature of water will increases and hence the volume. Water level will swell when it is heated. is called swelling. Drum level may be adjusted after swelling.
Water will start flowing from all bottom headers and starts raising in boiler.
Keep vigilance and allow water to fill in steam drum upto (NWL = 50 % of steam drum).
Switch off the transfer pump and close filling line isolation valve and all the panel/Economizer bottom header drain valves.
Caution for water filling in boiler steam drum:-
” While filling the water care should be taken to maintain the metal temperature above 21°C to avoid brittle fracture, hence the water temperature must be maintained to meet this requirement.”
VENTS SHOULD BE OPENED DURING BOILER WATER FILLING:-
|Sr. No.||VENTS SHOULD BE OPENED DURING BOILER WATER FILLING||CONDITION|
|1.||Furnace front water wall Drain Valves||Open|
|2.||Furnace Rear Water Wall Drain Valves||Open|
|3.||Furnace LHS Water Wall Drain Valves||Open|
|4.||Furnace RHS Water Wall Drain Valves||Open|
|5.||U Beam Hopper panel drain Valves||Open|
|6.||U beam Enclosure panel left & right hand drain valves||Open|
|7.||Superheater –I Enclosure panel left & right hand Drain Valves||Open|
|8.||Superheater –II Enclosure panel left & right hand drain Valves||Open|
|9.||Divisional Wall panel Drain valves||Open|
|10.||All Super heater drains Close||Open|
|11.||Economizer bottom header drain valve||Open|
|13.||Economiser top header vent valves||close|
|14.||Wing Wall Vents||close|
|15.||Super heater Vents||close|
|16.||Start Up vent||Open|
|17.||Furnace drain header outlet valve to IBD tank||close|
|18.||Filling Line Isolation Valve||Open|
|19.||CBD & IBD isolation valves||Close|
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