How to determine whether the amount of deoxidizer added to the boiler is too much or too little

Boiler feedwater deoxygenationIt is an important part of the operation and maintenance of the thermal system. Reasonable addition of boiler deaerator can reduce the corrosion of dissolved oxygen in water on the boiler body, pipelines, and heat exchange equipment. In daily operation, many maintenance personnel find it difficult to control the dosage of oxygen scavengers. Excessive or insufficient addition of oxygen scavengers can have varying degrees of impact on the boiler system. Mastering the method of judging whether the dosage is appropriate can help stabilize the operating conditions of the boiler and reduce equipment losses.

To determine whether the amount of deoxidizer added to the boiler is abnormal, the first step is to rely on the laboratory indicators of the water sample for judgment, which is also a commonly used method in on-site applications. Firstly, monitor the dissolved oxygen values in the feedwater, boiler water, and condensate water. If the dissolved oxygen detection results continue to be high, it mostly indicates insufficient addition of deoxidizer. When the dosage of the reagent is insufficient, it cannot fully react with dissolved oxygen in water, and the residual oxygen will continue to contact the metal inner wall, promoting oxidation corrosion. Long term operation can easily cause pitting corrosion and thinning of the pipe wall, shortening the service life of the pipeline and boiler heating surface.

If the residual content of deoxidizer in water sample testing continues to be higher than the process set control range, it indicates that the dosage of the reagent is too high. Excessive deoxidizer will form excess products in the water, some of which will increase the salt content of the boiler water, increase the probability of steam water co distillation, and affect steam quality. At the same time, excessive chemical decomposition may produce volatile substances that enter the subsequent heat exchange pipeline with steam, causing additional impact on the condensate system and increasing the cost of chemical procurement, resulting in material waste.

In addition to laboratory water quality testing, it can also be combined with boiler operation appearance and equipment status to assist in judgment. The typical manifestation of insufficient addition of deoxidizer is not only excessive dissolved oxygen, but also the discovery of rust deposits on the inner walls of pipelines, economizers, water heaters, and other locations. The water discharged from the sewage pipeline is prone to yellowing and rust impurities. For boilers that have been shut down for maintenance, check the inner wall of the heating surface. If there are many pitting corrosion pits, it is necessary to review the daily deoxygenation agent dosing plan and investigate whether long-term low-dose dosing is necessary.

When an excessive amount of deoxygenation agent is added, some types of agents may cause pH fluctuations in the water body after reaction, which can easily cause the pH of the boiler water to deviate from the control range. Under some working conditions, foam will increase, more impurities will be carried by steam, and abnormal attachments will appear on the inner wall of subsequent condensation equipment. For boiler systems equipped with online monitoring instruments, it is also possible to observe oxidation-reduction potential data, which remains in an abnormal range for a long time and can serve as a reference signal for imbalanced dosing of chemicals.

Before adjusting the actual dosage, it is necessary to distinguish the interfering factors to avoid misjudgment. Poor operating conditions, substandard water temperature, and poor exhaust of thermal deoxygenation equipment can also lead to high levels of dissolved oxygen in water, which cannot be solved simply by increasing deoxygenation agents. Fluctuations in feedwater flow rate, changes in water temperature, and adjustments in boiler load can also affect the efficiency of chemical reactions. Operations personnel need to ensure the stable operation of the thermal deoxygenation device before optimizing the chemical deoxygenation agent dosing plan.

The standardized adjustment process should be based on standard water sample testing data as the core basis. Representative water samples of feedwater, boiler water, and condensate water should be collected first, and dissolved oxygen, residual drug content, pH value, and other items should be tested and compared with the established control indicators of the enterprise. If it is confirmed that the dosage is insufficient, the dosing frequency of the metering pump can be slightly increased, adjusted in stages, and the water quality changes can be observed for 2 to 4 operating cycles; When it is confirmed that the dosage is excessive, gradually reduce the dosage and continuously track the decline of residual indicators. Do not make significant changes to the parameters at once.

In addition, there are differences in the reaction characteristics of different types of boiler deoxidizers, and the applicable control indicators are also different, so a unified standard cannot be applied. There are significant differences in the water quality control range between low-pressure boilers and medium high pressure power plant boilers. When customizing the dosing plan, it is necessary to refer to relevant specifications for boiler water treatment, and comprehensively develop it based on equipment parameters, feedwater quality, and operating load. Regularly keep records of drug dosage and water quality records to facilitate long-term comparison of drug dosage effects and form a stable operation and maintenance plan.

Overall, judgingBoiler deoxygenation agentWhether the dosage is reasonable is mainly based on water quality test data, supplemented by comprehensive analysis of equipment corrosion and steam water operation status. Adhere to a small adjustment of the dosing plan, avoid one-time increase or decrease in dosage, and cooperate with the thermal deoxygenation equipment to maintain the deoxygenation agent in an appropriate range, ensuring the smooth operation of the boiler thermal system.