What is boiler deaerator? Detailed explanation of the principle of action, applicable scenarios, and usage specifications

There is continuous dissolved oxygen inside the boiler water circulation system, which can cause electrochemical corrosion to metal components such as the boiler steam drum, water-cooled wall, pipeline, and economizer. Long term operation can easily lead to problems such as thinning of the pipe wall, pitting, perforation, leakage, and shutdown, shortening the service life of the entire thermal equipment. Boiler deaerator is a water treatment agent specifically added to the boiler feedwater system to remove dissolved oxygen from water and inhibit metal corrosion. It is widely used in water treatment conditions such as industrial steam boilers, hot water boilers, and thermal pipelines. The following text provides a complete explanation of the basic definition, mechanism of action, common types, key usage points, and supporting control requirements of boiler deoxygenation agents.

1、 Basic definition of boiler deoxidizer

Free oxygen is dissolved in boiler feedwater, make-up water, and circulating cooling water. Even after being treated by a thermal deaerator, trace amounts of dissolved oxygen will still remain, which cannot meet the water quality standards for long-term safe operation of boilers.

Boiler deoxygenation agentBelonging to boiler specific water treatment chemicals, when added to the water supply pipeline, deoxygenated water tank or steam drum, it can undergo chemical reactions with dissolved oxygen in the water, converting free oxygen consumption into harmless substances; At the same time, a dense protective film can be formed on the surface of the metal tube wall to block direct contact between oxygen, water vapor, and steel, slowing down the corrosion rate from both chemical reaction and physical protection dimensions. It is an indispensable chemical category in the boiler water quality operation and maintenance system.

2、 Core principle of boiler deoxygenation agent

1. Chemical reactions consume dissolved oxygen

The active components of the drug can selectively undergo oxidation-reduction reactions with free oxygen in water, converting dissolved oxygen into stable products that do not deposit scale or corrode equipment, significantly reducing the oxygen content index of the feedwater and cutting off the reaction substrate of oxygen corrosion from the source. This reaction can steadily proceed at room temperature or boiler operating temperature, and is suitable for continuous dynamic feeding of water.

2. Metal tube wall passivation film protection

The derivatives of deoxidizer decomposition or reaction can adsorb and adhere to the inner walls of boiler carbon steel and alloy steel, forming a uniform and dense inert passivation protective film. This film isolates corrosive media such as water, oxygen, and carbon dioxide from contact with the metal substrate, preventing continuous pitting and crevice corrosion of the pipe wall, and also slowing down the accumulation of secondary corrosion products.

3. Assist in regulating the acidity and alkalinity of water quality

Most composite boiler deoxidizers come with pH adjustment components, which can moderately increase the pH value of the feedwater, weaken hydrogen embrittlement corrosion caused by acidic water bodies, optimize the water environment inside the boiler, and form a dual anti-corrosion guarantee with deoxygenation effect, suitable for the water quality control needs of boilers with different pressure levels of medium and low pressure and high pressure.

3、 Classification and applicable working conditions of mainstream boiler deoxygenation agents on the market

1. Inorganic reducing deoxidizer

Representative categories include sodium sulfite products, which have been maturely used for a long time, have controllable costs, and have fast reaction speeds. They are commonly used in low-pressure small industrial hot water boilers and heating boilers. When using, it is necessary to control the dosage. Excessive dosage can increase the solid content in the water, and it is necessary to carry out simultaneous sewage discharge operations.

2. Organic composite deoxidizer

Mainly composed of oxime, carbazide, and amine composite agents, the reaction products have strong solubility and will not increase the salt content of the feedwater. It is not easy to cause problems such as steam and water co distillation in the steam drum and steam carrying water. It is suitable for equipment with high steam quality requirements such as medium and high pressure power plant boilers, large industrial steam boilers, and waste heat boilers, and is suitable for continuous large-scale thermal unit operation scenarios.

3. Low temperature dedicated deoxidizer

Designed for special operating conditions such as starting and stopping of thermal deaerators, low load operation, and low-temperature water supply, it can maintain stable deoxygenation reaction activity in low-temperature environments, making up for the shortcomings of insufficient deoxygenation efficiency in the low-temperature section of thermal deoxygenation. It is commonly used in intermittent operation boilers and backup boiler feedwater systems.

4、 Precautions for the Standard Dosing and Use of Boiler Deoxidizer

The dosage shall be determined by comprehensive calculation based on the rated evaporation capacity of the boiler, feed water flow rate, measured dissolved oxygen content, and feed water temperature. The concentration of the agent cannot be arbitrarily increased. Excessive dosage not only increases the operating cost of water treatment, but also the decomposition products of excess chemicals may affect the quality of steam; If the dosage is insufficient, the oxygen control cannot meet the standard, and the corrosion hazard persists.

Fixed injection point position, conventional selection of continuous quantitative injection at the outlet of the thermal deaerator and the inlet of the boiler feedwater pump, with the help of water flow stirring to achieve uniform dispersion of the agent, avoiding local high concentration or uneven distribution of the agent. It is recommended to use an automatic dosing device for continuous and uniform dosing, which has stronger water quality stability compared to manual intermittent dosing.

The storage of chemicals follows the chemical storage regulations, sealed and placed in a cool, dry, and ventilated warehouse, away from incompatible materials such as strong acids and oxidants. Special dosing buckets and measuring pumps are used for packaging and retrieval to avoid chemical contamination and failure.

Regularly sampling and testing water quality indicators such as dissolved oxygen, pH value of boiler water, and total iron content, dynamically adjusting the dosing plan based on the testing data, and forming a standardized water quality control process of "dosing testing adjustment".

It is not enough to rely solely on deoxidizers to solve all corrosion problems. Deoxidizers need to be used in conjunction with a complete set of water treatment solutions such as thermal deoxygenation, system closed overflow exhaust, and regular boiler blowdown to stabilize and control equipment corrosion rates.

5、 The practical value of using boiler deoxygenation agents reasonably

Reduce corrosion losses: effectively control wall pitting and leakage faults caused by oxygen corrosion, reduce the frequency of unplanned boiler shutdowns for maintenance, and maintain continuous and stable operation of the thermal system.

Extending the service life of equipment: slowing down the rate of corrosion and thinning of key components such as water-cooled walls, economizers, and steam pipelines, prolonging the overall service life of boilers, and reducing the investment in equipment updates, maintenance, and replacement of parts.

Ensure stable steam quality: The composite deoxidizer will not increase the salt content of the water body, reducing the problems of steam water co distillation and steam carrying salt. The back-end steam turbine and heat exchange equipment will not experience scaling or wear due to the accumulation of steam impurities.

Suitable for multiple types of boilers: from small heating and hot water boilers, industrial steam boilers to high-pressure boilers in power plants, all can be matched with suitable types of deoxidizers, with strong universality and easy standardization of water quality management for thermal enterprises.

Conclusion

Boiler deoxygenation agentIt is not a simple water purification additive, but a core water treatment agent for the anti-corrosion operation and maintenance of thermal system water quality. It relies on a dual mechanism of chemical reaction deoxygenation and pipe wall passivation to solve the common problem of dissolved oxygen corrosion in boiler operation.

In practical application, it is necessary to scientifically select and accurately quantify the dosage based on the boiler pressure level, operating load, and raw water quality indicators. At the same time, a complete water quality monitoring system should be provided to integrate the use of chemicals into the entire boiler water treatment plan. Standardized application of deoxidizers can continuously avoid various safety hazards caused by oxygen corrosion, ensuring long-term safe, economical, and stable operation of boilers.