Operating procedures for a deaerator

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1. Specifications of the deaerator:
Name, Item, Unit, Design Parameters
Deaerator Model: 85
Rated Output, t/h: 85
Operating Temperature, °C: 104
Inlet Water Pressure, MPa: 0.2
Diameter of O2 Removal Head, mm: 1500
Water Tank Volume, m3: 35
Weight, kg: 12,500
Date of Manufacture: 2002.3.20
Manufacturer: Yixing Mike Water Treatment Equipment Factory

2. Operating procedures for the deaerator:
2.1 Starting up the deaerator
2.1.1 Preparations, communications, and testing before startup:
① Prepare the required record forms, tools, and equipment； ②Contact the water treatment unit to prepare water supply for the deaerator ； ③Contact the thermal engineering team to activate the instruments and protections, and conduct protection tests as well as manual switching tests for the pressure/level regulators ； ④Contact the electrical department to measure the insulation of the electric door and restore power, then test operate the electric door. 2.1.2 Checks before startup: The following valves should be in the closed position: the water level gauge drain valve, the water tank drain valve, the feed valve to the boiler’s drain tank, the soft water valve, the deaerator drain valve, the steam inlet valve, the reboiling valve, the valves in front of and behind the water level regulator, the valves in front of and behind the pressure regulator, and the steam feed valve to the continuous blowdown expansion vessel ； The following valves should be in the open position: the upper and lower cocks on the water level gauge, the feed pump recirculation valve, and the deaerator vent valve. 2.1.3 Start-up without water in the deaerator: (1) Slowly open the steam inlet valve to raise the temperature of the water tank by 30~50°C per hour. ⑵ The bottom drain valve is opened to heat the water tank, allowing condensate to flow out. ⑶ When the temperature in the deaerator reaches 100°C or steam flows out of the exhaust valve vigorously, slightly open the soft water valve to supply water into the deaerator slowly, and gradually increase the steam inlet valve to maintain the pressure inside the deaerator at 0.02–0.06 MPa. ⑷ Continue to slowly open the steam valve, use steam to heat and flush the deaerator, and then close the drain valve. ⑸ Open the soft water valve to maintain the normal water level. ⑹ Once the deaerator level is normal, the drain valve can be opened, and soft water as well as the boiler drain valve can be used to adjust the level to the proper value. ⑺ Open the reboiler door if necessary, depending on the tank temperature. 2.1.4 Start-up with water in the deaerator. ⑴ Open the main soft water valve to supply water to the deaerator. ⑵ Open the steam inlet valve and adjust it manually using the regulator. ⑶ When the water level reaches normal levels, the drain valve can be opened slowly. ⑷ Once the water level, pressure, water temperature, and exhaust steam conditions in the deaerator are normal, the thermal control team can be instructed to activate the pressure and water level automatic regulators. ⑸ Transfer the steam from the continuous blowdown expansion vessel to the deaerator. 2.2 Normal maintenance of the deaerator 2.2.1 During normal operation of the deaerator, the water level should be maintained at: 80%~100%. The internal pressure is maintained at: 0.02 MPa. The water temperature in the tank is maintained at: 100~106℃. 2.2.2 Maintain the feedwater in a saturated state to ensure an appropriate oxygen content. 2.2.3 Keep the floor and equipment clean. 2.2.4 The pressure safety valve shall not leak steam and shall not operate erroneously. 2.2.5 The deaerator overflow device shall not malfunction nor leak. 2.2.6 Not applicable to the overhead exhaust valve. 2.2.7 When the drain pump is supplying water properly, minimize the amount of soft water added; it is not allowed to add large quantities of soft water, resulting in overflow in the boiler’s drain tank. 2.2.8 Pay regular attention to pressure and the operation of the water level regulator; switch to manual mode in case of failure. 2.2.9 The steam source for the deaerator is supplied by stage I superheated steam or a temperature-reducing pressure regulator. 2.3 Shutdown of the deaerator ⑴ Switch the pressure and level regulators to manual mode. ⑵ They are the valves that lead to the steam valves, the continuous blowdown expansion vessel valves, and the reboiling valve. ⑶ Close the soft water inlet valve. ⑷ Close the feed valve to the boiler drain tank and the drain valve of the deaerator. ⑸ Switch the water pump system to operate with another deaerator. 2.4 Accident Handling of Deaerators 2.4.1 Drop in Deaerator Pressure ⑴ Causes of Pressure Drop ① Failure of the pressure automatic regulator, insufficient or interrupted supply of heating steam ； ② Excessive and too rapid hydration, as well as too low hydration temperature ； ③ The meter is malfunctioning. ⑵ Handling: ① Switch the pressure automatic regulator to manual mode; contact the thermal treatment team. If there is insufficient heating steam, increase the steam supply valve for Furnace #5 to keep the pressure in the deaerator within the specified range ； ②Control the water replenishment rate appropriately and make timely adjustments ； ③The pressure gauge is malfunctioning; monitor closely by referring to other instruments, and inform the thermal engineering team to restore it as soon as possible. 2.4.2 Rise in deaerator pressure ⑴ Causes of pressure rise ① Failure of automatic pressure control ； ② During Phase I, the heating load increases and the pressure rises ； ③ The outlet pressure of the temperature and pressure reducer increases. ⑵ Treatment for increased pressure: ① Switch the pressure automatic regulator to manual mode, close the steam inlet valve and reduce the flow at the steam inlet valve of the soft water heater, in order to lower the pressure inside the deaerator ； ② When the deaerator pressure is restored, pay attention to monitoring the reseating of the safety valve; if any sticking is detected, contact the relevant personnel for handling promptly. 2.4.3 Vibration in the deaerator ⑴ Causes ① Overloading of the deaerator and fluctuations in pressure at the deaeration head, resulting in oscillations in the water inlet pipe ； ② Excessive hydration or uneven flow that is inconsistent in volume ； ③ A sudden drop in pressure inside the deaerator caused foaming of the steam and water. ⑵ Treatment: ① Reduce the deaerator load and adjust it to restore normal pressure in the deaerator ； ② Ensure even water addition and an appropriate water supply rate ； ③ Vibration occurs during startup, controlling the rate of temperature and pressure increase. 2.4.4 Increase in oxygen content ⑴ Reasons for the increase in oxygen content ① Improper adjustment; water temperature not reaching saturation ； ② The opening degree of the residual steam vent valve is insufficient ； ③ Excessive water inflow, too low water inlet temperature ； ④ Air is leaking in through the gasket of the sampling door. ⑵ For handling ①, adjust and control the water supply volume in a timely manner, maintain the normal inlet water temperature, and keep the feed water in a saturated state ； ② The gasket at the sampling door is leaking; contact to have it replaced ； ③ Internal defects in the deaerator require that repairs be halted.