Deaerator Start-Up and Shutdown Procedures


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Deaerator Start-Up and Shutdown Procedures

Pre-start checks and operations

(1) Vent valve shall be wide open.
(At low load start, it may be necessary to throttle valve slightly to increase the operating pressure, but vent valve not to be fully close in any case.)
(2) Steam, condensate or water and feed water suction valve shall be closed.
(3) All block valve of instrument is to be open.
(4) All control, alarm and switch is on proper function.
(5) Temperature pressure gauge and instrument shall be calibrated.


Initial state (STARTUP)

Before water and steam flow into the equipment, check below contents.
(1) Open the vent completely. In case of very low pressure operation vent throttle valve is slightly closed to maintain the pressure of tank But don’t close vent completely at any case.
(2) Check the safety valve.
(3) Check to see that all local instruments are operation and indicating correctly.
(4) Check the degree accuracy of temperature gage, pressure gage and all measurement instruments.


Normal Start-up

(1) Open slowly the condensate or water supply valve.
(2) Fill-up water to storage tank up to 60-70% level.
(3) Stop the condensate or water supply.
(4) Open slowly the sparger steam supply valve to heat the water within storage tank.
(5) After water temperature is increased to proper temperature, close the sparger steam supply valve and stop and valve operation until vapor fume disappear from vent pipe.
(6) Above step 1- 5 may be omitted if feed water can be recirculated through minimum flow line.
(7) Open slowly the condensate or water supply valve to 15-30% load flow rate.
(8) Open step by step the main steam supply valve until operating pressure will be rate.
(Caution: Do not fill the deaerator with steam first and then supply the condensate or water. This operation will cause the damage of internals and the partial collapse of shell.)
(9) Adjust the steam supply valve to Auto mode.
(10) Open minimum flow valve of feed water pump discharge.
(11) Start feed water pump.
(12) Recirculate feed water through minimum flow line until feed water temperature is increased to near operating temperature.
(Step 10 & 12 can be omitted in case that water is heated by steam of step 1-5)
(13) During recirculation operation, drain valve shall be open to protect the increase of water level and the suspension of eater supply.
(14) Adjust the water supply valve to Auto mode when water level is near normal level.
(15) Open slowly the discharge valve of feed water pump and supply the feed water to boiler or its related equipment.
(16) Load of deaerator will be increased as the discharge valve of feed water pump is more open.
(17) After normal operation is maintained with proper load than 30minutes, vent valve can be closed to one or two turns.
(Normally it indicates sufficient venting if steam fume rises approximately one meter above the end of vent pipe.)
(18) Now deaerator is ready for continuous operation.


Normal Shutdown

(1) Close slowly the boiler feed water pump discharge valve.
(2) Close the condensate or water supply valve.
(3) Isolate the main steam supply valve.
(4) Open the atmospheric vent valve fully to expel any remaining steam in tank.
(5) If it should be necessary to drain the tank. Start drain after wide opening of vent valve.
(Draining without sufficient venting will cause the undue stress on shell by vacuum.)


Emergency Shutdown

(1) Isolate the main steam supply valve.
(2) Close the condensate or water supply valve.
(3) Close the boiler feed water pump discharge valve.
(4) Open the atmospheric vent valve fully to expel any remaining steam in tank.
(5) If it should be necessary to drain the tank.
Start drain after wide opening of vent valve.
(Draining without sufficient venting will cause the undue stress on shell by vacuum.)