Hydrogenation “One Question per Day” Question 3
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Specific requirements and daily maintenance for deaerators. Basic requirements: ① The water must be heated to the saturation temperature at the pressure of the deaerator. ②The amount of steam used for heating must be appropriate; attention should be paid to balancing the water volume and steam volume to ensure that the water in the deaerator remains in a boiling state. Insufficient steam volume leads to a drop in pressure, resulting in reduced deoxygenation efficiency. Excessive steam volume causes pressure to rise, triggering the water seal mechanism, which is neither economical nor safe. ③The steam discharge valve at the top of the deaerator must be kept at a certain opening degree to ensure that the gases formed can be discharged smoothly, but it should not be too open. ④The amount of water supplied as a supplement should be stable to avoid pressure fluctuations, which could reduce the deoxygenation efficiency. Normal maintenance: ① Maintain the deaerator pressure at 0.02 MPa gauge pressure and the water temperature at 104°C. ②The oxygen content in the effluent should be less than 15 μg/L. ③The water tank level is at 2/3. ④The water seal tube is often filled with water. ⑤Regularly flush the water level gauge.
The operation and maintenance of deaerators do require strict control of parameters, with steam level balance and exhaust gas control being particularly critical. A few additional tips: It is recommended to install flow meters on the water inlet pipes of the deaerator to monitor fluctuations in the amount of water added in real time. Since installing such meters in our plant, pressure stability has improved significantly ； The opening degree of the exhaust valve can be fine-tuned according to the pH value of the condensate water; increasing the opening degree slightly when the pH value is low yields good results ； The oxygen content in the water should be checked weekly using a portable dissolved oxygen meter, as this method can detect early problems more effectively than online instruments. These parameter adjustments still need to be carried out in consideration of the specific characteristics of the equipment; if possible, it is best to keep a record of operational logs to track trends over time.
Regarding the control of the steam level balance in the deaerator, here is a practical tip: a pressure transmitter can be installed after the steam control valve, and three-variable control can be implemented using the DCS system (steam pressure, feedwater flow rate, and deaerator level). This approach provides greater stability compared to manual adjustment alone. After the renovation of our factory, the number of times the oxygen level exceeded the limit decreased by about 70%. Additionally, it should be noted that during winter operation, attention must be paid to the drainage of steam pipes to prevent water hammer from damaging the equipment.